logical.h File Reference

#include "access/xlog.h"
#include "access/xlogreader.h"
#include "replication/output_plugin.h"
#include "replication/slot.h"

Include dependency graph for logical.h:

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Go to the source code of this file.

Data Structures
struct	LogicalDecodingContext

Typedefs
typedef void(*	LogicalOutputPluginWriterWrite) (struct LogicalDecodingContext *lr, XLogRecPtr Ptr, TransactionId xid, bool last_write)
typedef LogicalOutputPluginWriterWrite	LogicalOutputPluginWriterPrepareWrite
typedef void(*	LogicalOutputPluginWriterUpdateProgress) (struct LogicalDecodingContext *lr, XLogRecPtr Ptr, TransactionId xid, bool skipped_xact)
typedef struct LogicalDecodingContext	LogicalDecodingContext

Functions
void	CheckLogicalDecodingRequirements (void)
LogicalDecodingContext *	CreateInitDecodingContext (const char *plugin, List *output_plugin_options, bool need_full_snapshot, XLogRecPtr restart_lsn, XLogReaderRoutine *xl_routine, LogicalOutputPluginWriterPrepareWrite prepare_write, LogicalOutputPluginWriterWrite do_write, LogicalOutputPluginWriterUpdateProgress update_progress)
LogicalDecodingContext *	CreateDecodingContext (XLogRecPtr start_lsn, List *output_plugin_options, bool fast_forward, XLogReaderRoutine *xl_routine, LogicalOutputPluginWriterPrepareWrite prepare_write, LogicalOutputPluginWriterWrite do_write, LogicalOutputPluginWriterUpdateProgress update_progress)
void	DecodingContextFindStartpoint (LogicalDecodingContext *ctx)
bool	DecodingContextReady (LogicalDecodingContext *ctx)
void	FreeDecodingContext (LogicalDecodingContext *ctx)
void	LogicalIncreaseXminForSlot (XLogRecPtr current_lsn, TransactionId xmin)
void	LogicalIncreaseRestartDecodingForSlot (XLogRecPtr current_lsn, XLogRecPtr restart_lsn)
void	LogicalConfirmReceivedLocation (XLogRecPtr lsn)
bool	filter_prepare_cb_wrapper (LogicalDecodingContext *ctx, TransactionId xid, const char *gid)
bool	filter_by_origin_cb_wrapper (LogicalDecodingContext *ctx, RepOriginId origin_id)
void	ResetLogicalStreamingState (void)
void	UpdateDecodingStats (LogicalDecodingContext *ctx)
bool	LogicalReplicationSlotHasPendingWal (XLogRecPtr end_of_wal)
XLogRecPtr	LogicalSlotAdvanceAndCheckSnapState (XLogRecPtr moveto, bool *found_consistent_snapshot)

Typedef Documentation

LogicalDecodingContext

typedef struct LogicalDecodingContext LogicalDecodingContext

LogicalOutputPluginWriterPrepareWrite

typedef LogicalOutputPluginWriterWrite LogicalOutputPluginWriterPrepareWrite

Definition at line 25 of file logical.h.

LogicalOutputPluginWriterUpdateProgress

typedef void(* LogicalOutputPluginWriterUpdateProgress) (struct LogicalDecodingContext *lr, XLogRecPtr Ptr, TransactionId xid, bool skipped_xact)

Definition at line 27 of file logical.h.

LogicalOutputPluginWriterWrite

typedef void(* LogicalOutputPluginWriterWrite) (struct LogicalDecodingContext *lr, XLogRecPtr Ptr, TransactionId xid, bool last_write)

Definition at line 19 of file logical.h.

Function Documentation

CheckLogicalDecodingRequirements()

void CheckLogicalDecodingRequirements

(

void

)

Definition at line 109 of file logical.c.

{
    CheckSlotRequirements();
 
    /*
     * NB: Adding a new requirement likely means that RestoreSlotFromDisk()
     * needs the same check.
     */
 
    if (wal_level < WAL_LEVEL_LOGICAL)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("logical decoding requires \"wal_level\" >= \"logical\"")));
 
    if (MyDatabaseId == InvalidOid)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("logical decoding requires a database connection")));
 
    if (RecoveryInProgress())
    {
        /*
         * This check may have race conditions, but whenever
         * XLOG_PARAMETER_CHANGE indicates that wal_level has changed, we
         * verify that there are no existing logical replication slots. And to
         * avoid races around creating a new slot,
         * CheckLogicalDecodingRequirements() is called once before creating
         * the slot, and once when logical decoding is initially starting up.
         */
        if (GetActiveWalLevelOnStandby() < WAL_LEVEL_LOGICAL)
            ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("logical decoding on standby requires \"wal_level\" >= \"logical\" on the primary")));
    }
}

References CheckSlotRequirements(), ereport, errcode(), errmsg(), ERROR, GetActiveWalLevelOnStandby(), InvalidOid, MyDatabaseId, RecoveryInProgress(), wal_level, and WAL_LEVEL_LOGICAL.

Referenced by copy_replication_slot(), CreateInitDecodingContext(), CreateReplicationSlot(), pg_create_logical_replication_slot(), pg_logical_slot_get_changes_guts(), and StartLogicalReplication().

CreateDecodingContext()

LogicalDecodingContext * CreateDecodingContext	(	XLogRecPtr	start_lsn,
		List *	output_plugin_options,
		bool	fast_forward,
		XLogReaderRoutine *	xl_routine,
		LogicalOutputPluginWriterPrepareWrite	prepare_write,
		LogicalOutputPluginWriterWrite	do_write,
		LogicalOutputPluginWriterUpdateProgress	update_progress
	)

Definition at line 496 of file logical.c.

{
    LogicalDecodingContext *ctx;
    ReplicationSlot *slot;
    MemoryContext old_context;
 
    /* shorter lines... */
    slot = MyReplicationSlot;
 
    /* first some sanity checks that are unlikely to be violated */
    if (slot == NULL)
        elog(ERROR, "cannot perform logical decoding without an acquired slot");
 
    /* make sure the passed slot is suitable, these are user facing errors */
    if (SlotIsPhysical(slot))
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("cannot use physical replication slot for logical decoding")));
 
    /*
     * We need to access the system tables during decoding to build the
     * logical changes unless we are in fast_forward mode where no changes are
     * generated.
     */
    if (slot->data.database != MyDatabaseId && !fast_forward)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("replication slot \"%s\" was not created in this database",
                        NameStr(slot->data.name))));
 
    /*
     * The slots being synced from the primary can't be used for decoding as
     * they are used after failover. However, we do allow advancing the LSNs
     * during the synchronization of slots. See update_local_synced_slot.
     */
    if (RecoveryInProgress() && slot->data.synced && !IsSyncingReplicationSlots())
        ereport(ERROR,
                errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                errmsg("cannot use replication slot \"%s\" for logical decoding",
                       NameStr(slot->data.name)),
                errdetail("This replication slot is being synchronized from the primary server."),
                errhint("Specify another replication slot."));
 
    /* slot must be valid to allow decoding */
    Assert(slot->data.invalidated == RS_INVAL_NONE);
    Assert(slot->data.restart_lsn != InvalidXLogRecPtr);
 
    if (start_lsn == InvalidXLogRecPtr)
    {
        /* continue from last position */
        start_lsn = slot->data.confirmed_flush;
    }
    else if (start_lsn < slot->data.confirmed_flush)
    {
        /*
         * It might seem like we should error out in this case, but it's
         * pretty common for a client to acknowledge a LSN it doesn't have to
         * do anything for, and thus didn't store persistently, because the
         * xlog records didn't result in anything relevant for logical
         * decoding. Clients have to be able to do that to support synchronous
         * replication.
         *
         * Starting at a different LSN than requested might not catch certain
         * kinds of client errors; so the client may wish to check that
         * confirmed_flush_lsn matches its expectations.
         */
        elog(LOG, "%X/%X has been already streamed, forwarding to %X/%X",
             LSN_FORMAT_ARGS(start_lsn),
             LSN_FORMAT_ARGS(slot->data.confirmed_flush));
 
        start_lsn = slot->data.confirmed_flush;
    }
 
    ctx = StartupDecodingContext(output_plugin_options,
                                 start_lsn, InvalidTransactionId, false,
                                 fast_forward, false, xl_routine, prepare_write,
                                 do_write, update_progress);
 
    /* call output plugin initialization callback */
    old_context = MemoryContextSwitchTo(ctx->context);
    if (ctx->callbacks.startup_cb != NULL)
        startup_cb_wrapper(ctx, &ctx->options, false);
    MemoryContextSwitchTo(old_context);
 
    /*
     * We allow decoding of prepared transactions when the two_phase is
     * enabled at the time of slot creation, or when the two_phase option is
     * given at the streaming start, provided the plugin supports all the
     * callbacks for two-phase.
     */
    ctx->twophase &= (slot->data.two_phase || ctx->twophase_opt_given);
 
    /* Mark slot to allow two_phase decoding if not already marked */
    if (ctx->twophase && !slot->data.two_phase)
    {
        SpinLockAcquire(&slot->mutex);
        slot->data.two_phase = true;
        slot->data.two_phase_at = start_lsn;
        SpinLockRelease(&slot->mutex);
        ReplicationSlotMarkDirty();
        ReplicationSlotSave();
        SnapBuildSetTwoPhaseAt(ctx->snapshot_builder, start_lsn);
    }
 
    ctx->reorder->output_rewrites = ctx->options.receive_rewrites;
 
    ereport(LOG,
            (errmsg("starting logical decoding for slot \"%s\"",
                    NameStr(slot->data.name)),
             errdetail("Streaming transactions committing after %X/%X, reading WAL from %X/%X.",
                       LSN_FORMAT_ARGS(slot->data.confirmed_flush),
                       LSN_FORMAT_ARGS(slot->data.restart_lsn))));
 
    return ctx;
}

References Assert(), LogicalDecodingContext::callbacks, ReplicationSlotPersistentData::confirmed_flush, LogicalDecodingContext::context, ReplicationSlot::data, data, ReplicationSlotPersistentData::database, elog, ereport, errcode(), errdetail(), errhint(), errmsg(), ERROR, ReplicationSlotPersistentData::invalidated, InvalidTransactionId, InvalidXLogRecPtr, IsSyncingReplicationSlots(), LOG, LSN_FORMAT_ARGS, MemoryContextSwitchTo(), ReplicationSlot::mutex, MyDatabaseId, MyReplicationSlot, ReplicationSlotPersistentData::name, NameStr, LogicalDecodingContext::options, ReorderBuffer::output_rewrites, OutputPluginOptions::receive_rewrites, RecoveryInProgress(), LogicalDecodingContext::reorder, ReplicationSlotMarkDirty(), ReplicationSlotSave(), ReplicationSlotPersistentData::restart_lsn, RS_INVAL_NONE, SlotIsPhysical, SnapBuildSetTwoPhaseAt(), LogicalDecodingContext::snapshot_builder, SpinLockAcquire, SpinLockRelease, OutputPluginCallbacks::startup_cb, startup_cb_wrapper(), StartupDecodingContext(), ReplicationSlotPersistentData::synced, ReplicationSlotPersistentData::two_phase, ReplicationSlotPersistentData::two_phase_at, LogicalDecodingContext::twophase, and LogicalDecodingContext::twophase_opt_given.

Referenced by LogicalReplicationSlotHasPendingWal(), LogicalSlotAdvanceAndCheckSnapState(), pg_logical_slot_get_changes_guts(), and StartLogicalReplication().

CreateInitDecodingContext()

LogicalDecodingContext * CreateInitDecodingContext	(	const char *	plugin,
		List *	output_plugin_options,
		bool	need_full_snapshot,
		XLogRecPtr	restart_lsn,
		XLogReaderRoutine *	xl_routine,
		LogicalOutputPluginWriterPrepareWrite	prepare_write,
		LogicalOutputPluginWriterWrite	do_write,
		LogicalOutputPluginWriterUpdateProgress	update_progress
	)

Definition at line 330 of file logical.c.

{
    TransactionId xmin_horizon = InvalidTransactionId;
    ReplicationSlot *slot;
    NameData    plugin_name;
    LogicalDecodingContext *ctx;
    MemoryContext old_context;
 
    /*
     * On a standby, this check is also required while creating the slot.
     * Check the comments in the function.
     */
    CheckLogicalDecodingRequirements();
 
    /* shorter lines... */
    slot = MyReplicationSlot;
 
    /* first some sanity checks that are unlikely to be violated */
    if (slot == NULL)
        elog(ERROR, "cannot perform logical decoding without an acquired slot");
 
    if (plugin == NULL)
        elog(ERROR, "cannot initialize logical decoding without a specified plugin");
 
    /* Make sure the passed slot is suitable. These are user facing errors. */
    if (SlotIsPhysical(slot))
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("cannot use physical replication slot for logical decoding")));
 
    if (slot->data.database != MyDatabaseId)
        ereport(ERROR,
                (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                 errmsg("replication slot \"%s\" was not created in this database",
                        NameStr(slot->data.name))));
 
    if (IsTransactionState() &&
        GetTopTransactionIdIfAny() != InvalidTransactionId)
        ereport(ERROR,
                (errcode(ERRCODE_ACTIVE_SQL_TRANSACTION),
                 errmsg("cannot create logical replication slot in transaction that has performed writes")));
 
    /*
     * Register output plugin name with slot.  We need the mutex to avoid
     * concurrent reading of a partially copied string.  But we don't want any
     * complicated code while holding a spinlock, so do namestrcpy() outside.
     */
    namestrcpy(&plugin_name, plugin);
    SpinLockAcquire(&slot->mutex);
    slot->data.plugin = plugin_name;
    SpinLockRelease(&slot->mutex);
 
    if (XLogRecPtrIsInvalid(restart_lsn))
        ReplicationSlotReserveWal();
    else
    {
        SpinLockAcquire(&slot->mutex);
        slot->data.restart_lsn = restart_lsn;
        SpinLockRelease(&slot->mutex);
    }
 
    /* ----
     * This is a bit tricky: We need to determine a safe xmin horizon to start
     * decoding from, to avoid starting from a running xacts record referring
     * to xids whose rows have been vacuumed or pruned
     * already. GetOldestSafeDecodingTransactionId() returns such a value, but
     * without further interlock its return value might immediately be out of
     * date.
     *
     * So we have to acquire the ProcArrayLock to prevent computation of new
     * xmin horizons by other backends, get the safe decoding xid, and inform
     * the slot machinery about the new limit. Once that's done the
     * ProcArrayLock can be released as the slot machinery now is
     * protecting against vacuum.
     *
     * Note that, temporarily, the data, not just the catalog, xmin has to be
     * reserved if a data snapshot is to be exported.  Otherwise the initial
     * data snapshot created here is not guaranteed to be valid. After that
     * the data xmin doesn't need to be managed anymore and the global xmin
     * should be recomputed. As we are fine with losing the pegged data xmin
     * after crash - no chance a snapshot would get exported anymore - we can
     * get away with just setting the slot's
     * effective_xmin. ReplicationSlotRelease will reset it again.
     *
     * ----
     */
    LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
 
    xmin_horizon = GetOldestSafeDecodingTransactionId(!need_full_snapshot);
 
    SpinLockAcquire(&slot->mutex);
    slot->effective_catalog_xmin = xmin_horizon;
    slot->data.catalog_xmin = xmin_horizon;
    if (need_full_snapshot)
        slot->effective_xmin = xmin_horizon;
    SpinLockRelease(&slot->mutex);
 
    ReplicationSlotsComputeRequiredXmin(true);
 
    LWLockRelease(ProcArrayLock);
 
    ReplicationSlotMarkDirty();
    ReplicationSlotSave();
 
    ctx = StartupDecodingContext(NIL, restart_lsn, xmin_horizon,
                                 need_full_snapshot, false, true,
                                 xl_routine, prepare_write, do_write,
                                 update_progress);
 
    /* call output plugin initialization callback */
    old_context = MemoryContextSwitchTo(ctx->context);
    if (ctx->callbacks.startup_cb != NULL)
        startup_cb_wrapper(ctx, &ctx->options, true);
    MemoryContextSwitchTo(old_context);
 
    /*
     * We allow decoding of prepared transactions when the two_phase is
     * enabled at the time of slot creation, or when the two_phase option is
     * given at the streaming start, provided the plugin supports all the
     * callbacks for two-phase.
     */
    ctx->twophase &= slot->data.two_phase;
 
    ctx->reorder->output_rewrites = ctx->options.receive_rewrites;
 
    return ctx;
}

References LogicalDecodingContext::callbacks, ReplicationSlotPersistentData::catalog_xmin, CheckLogicalDecodingRequirements(), LogicalDecodingContext::context, ReplicationSlot::data, ReplicationSlotPersistentData::database, ReplicationSlot::effective_catalog_xmin, ReplicationSlot::effective_xmin, elog, ereport, errcode(), errmsg(), ERROR, GetOldestSafeDecodingTransactionId(), GetTopTransactionIdIfAny(), InvalidTransactionId, IsTransactionState(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), MemoryContextSwitchTo(), ReplicationSlot::mutex, MyDatabaseId, MyReplicationSlot, ReplicationSlotPersistentData::name, NameStr, namestrcpy(), NIL, LogicalDecodingContext::options, ReorderBuffer::output_rewrites, plugin, ReplicationSlotPersistentData::plugin, OutputPluginOptions::receive_rewrites, LogicalDecodingContext::reorder, ReplicationSlotMarkDirty(), ReplicationSlotReserveWal(), ReplicationSlotSave(), ReplicationSlotsComputeRequiredXmin(), ReplicationSlotPersistentData::restart_lsn, SlotIsPhysical, SpinLockAcquire, SpinLockRelease, OutputPluginCallbacks::startup_cb, startup_cb_wrapper(), StartupDecodingContext(), ReplicationSlotPersistentData::two_phase, LogicalDecodingContext::twophase, and XLogRecPtrIsInvalid.

Referenced by create_logical_replication_slot(), and CreateReplicationSlot().

DecodingContextFindStartpoint()

void DecodingContextFindStartpoint

(

LogicalDecodingContext *

ctx

)

Definition at line 631 of file logical.c.

{
    ReplicationSlot *slot = ctx->slot;
 
    /* Initialize from where to start reading WAL. */
    XLogBeginRead(ctx->reader, slot->data.restart_lsn);
 
    elog(DEBUG1, "searching for logical decoding starting point, starting at %X/%X",
         LSN_FORMAT_ARGS(slot->data.restart_lsn));
 
    /* Wait for a consistent starting point */
    for (;;)
    {
        XLogRecord *record;
        char       *err = NULL;
 
        /* the read_page callback waits for new WAL */
        record = XLogReadRecord(ctx->reader, &err);
        if (err)
            elog(ERROR, "could not find logical decoding starting point: %s", err);
        if (!record)
            elog(ERROR, "could not find logical decoding starting point");
 
        LogicalDecodingProcessRecord(ctx, ctx->reader);
 
        /* only continue till we found a consistent spot */
        if (DecodingContextReady(ctx))
            break;
 
        CHECK_FOR_INTERRUPTS();
    }
 
    SpinLockAcquire(&slot->mutex);
    slot->data.confirmed_flush = ctx->reader->EndRecPtr;
    if (slot->data.two_phase)
        slot->data.two_phase_at = ctx->reader->EndRecPtr;
    SpinLockRelease(&slot->mutex);
}

References CHECK_FOR_INTERRUPTS, ReplicationSlotPersistentData::confirmed_flush, ReplicationSlot::data, DEBUG1, DecodingContextReady(), elog, XLogReaderState::EndRecPtr, err(), ERROR, LogicalDecodingProcessRecord(), LSN_FORMAT_ARGS, ReplicationSlot::mutex, LogicalDecodingContext::reader, ReplicationSlotPersistentData::restart_lsn, LogicalDecodingContext::slot, SpinLockAcquire, SpinLockRelease, ReplicationSlotPersistentData::two_phase, ReplicationSlotPersistentData::two_phase_at, XLogBeginRead(), and XLogReadRecord().

Referenced by create_logical_replication_slot(), and CreateReplicationSlot().

DecodingContextReady()

bool DecodingContextReady

(

LogicalDecodingContext *

ctx

)

Definition at line 622 of file logical.c.

{
    return SnapBuildCurrentState(ctx->snapshot_builder) == SNAPBUILD_CONSISTENT;
}

References SNAPBUILD_CONSISTENT, SnapBuildCurrentState(), and LogicalDecodingContext::snapshot_builder.

Referenced by DecodingContextFindStartpoint(), and LogicalSlotAdvanceAndCheckSnapState().

filter_by_origin_cb_wrapper()

bool filter_by_origin_cb_wrapper	(	LogicalDecodingContext *	ctx,
		RepOriginId	origin_id
	)

Definition at line 1197 of file logical.c.

{
    LogicalErrorCallbackState state;
    ErrorContextCallback errcallback;
    bool        ret;
 
    Assert(!ctx->fast_forward);
 
    /* Push callback + info on the error context stack */
    state.ctx = ctx;
    state.callback_name = "filter_by_origin";
    state.report_location = InvalidXLogRecPtr;
    errcallback.callback = output_plugin_error_callback;
    errcallback.arg = &state;
    errcallback.previous = error_context_stack;
    error_context_stack = &errcallback;
 
    /* set output state */
    ctx->accept_writes = false;
    ctx->end_xact = false;
 
    /* do the actual work: call callback */
    ret = ctx->callbacks.filter_by_origin_cb(ctx, origin_id);
 
    /* Pop the error context stack */
    error_context_stack = errcallback.previous;
 
    return ret;
}

References LogicalDecodingContext::accept_writes, ErrorContextCallback::arg, Assert(), ErrorContextCallback::callback, LogicalDecodingContext::callbacks, LogicalDecodingContext::end_xact, error_context_stack, LogicalDecodingContext::fast_forward, OutputPluginCallbacks::filter_by_origin_cb, InvalidXLogRecPtr, output_plugin_error_callback(), and ErrorContextCallback::previous.

Referenced by FilterByOrigin().

filter_prepare_cb_wrapper()

bool filter_prepare_cb_wrapper	(	LogicalDecodingContext *	ctx,
		TransactionId	xid,
		const char *	gid
	)

Definition at line 1165 of file logical.c.

{
    LogicalErrorCallbackState state;
    ErrorContextCallback errcallback;
    bool        ret;
 
    Assert(!ctx->fast_forward);
 
    /* Push callback + info on the error context stack */
    state.ctx = ctx;
    state.callback_name = "filter_prepare";
    state.report_location = InvalidXLogRecPtr;
    errcallback.callback = output_plugin_error_callback;
    errcallback.arg = &state;
    errcallback.previous = error_context_stack;
    error_context_stack = &errcallback;
 
    /* set output state */
    ctx->accept_writes = false;
    ctx->end_xact = false;
 
    /* do the actual work: call callback */
    ret = ctx->callbacks.filter_prepare_cb(ctx, xid, gid);
 
    /* Pop the error context stack */
    error_context_stack = errcallback.previous;
 
    return ret;
}

References LogicalDecodingContext::accept_writes, ErrorContextCallback::arg, Assert(), ErrorContextCallback::callback, LogicalDecodingContext::callbacks, LogicalDecodingContext::end_xact, error_context_stack, LogicalDecodingContext::fast_forward, OutputPluginCallbacks::filter_prepare_cb, InvalidXLogRecPtr, output_plugin_error_callback(), and ErrorContextCallback::previous.

Referenced by FilterPrepare().

FreeDecodingContext()

void FreeDecodingContext

(

LogicalDecodingContext *

ctx

)

Definition at line 675 of file logical.c.

{
    if (ctx->callbacks.shutdown_cb != NULL)
        shutdown_cb_wrapper(ctx);
 
    ReorderBufferFree(ctx->reorder);
    FreeSnapshotBuilder(ctx->snapshot_builder);
    XLogReaderFree(ctx->reader);
    MemoryContextDelete(ctx->context);
}

References LogicalDecodingContext::callbacks, LogicalDecodingContext::context, FreeSnapshotBuilder(), MemoryContextDelete(), LogicalDecodingContext::reader, LogicalDecodingContext::reorder, ReorderBufferFree(), OutputPluginCallbacks::shutdown_cb, shutdown_cb_wrapper(), LogicalDecodingContext::snapshot_builder, and XLogReaderFree().

Referenced by create_logical_replication_slot(), CreateReplicationSlot(), LogicalReplicationSlotHasPendingWal(), LogicalSlotAdvanceAndCheckSnapState(), pg_logical_slot_get_changes_guts(), and StartLogicalReplication().

LogicalConfirmReceivedLocation()

void LogicalConfirmReceivedLocation

(

XLogRecPtr

lsn

)

Definition at line 1818 of file logical.c.

{
    Assert(lsn != InvalidXLogRecPtr);
 
    /* Do an unlocked check for candidate_lsn first. */
    if (MyReplicationSlot->candidate_xmin_lsn != InvalidXLogRecPtr ||
        MyReplicationSlot->candidate_restart_valid != InvalidXLogRecPtr)
    {
        bool        updated_xmin = false;
        bool        updated_restart = false;
 
        SpinLockAcquire(&MyReplicationSlot->mutex);
 
        /*
         * Prevent moving the confirmed_flush backwards, as this could lead to
         * data duplication issues caused by replicating already replicated
         * changes.
         *
         * This can happen when a client acknowledges an LSN it doesn't have
         * to do anything for, and thus didn't store persistently. After a
         * restart, the client can send the prior LSN that it stored
         * persistently as an acknowledgement, but we need to ignore such an
         * LSN. See similar case handling in CreateDecodingContext.
         */
        if (lsn > MyReplicationSlot->data.confirmed_flush)
            MyReplicationSlot->data.confirmed_flush = lsn;
 
        /* if we're past the location required for bumping xmin, do so */
        if (MyReplicationSlot->candidate_xmin_lsn != InvalidXLogRecPtr &&
            MyReplicationSlot->candidate_xmin_lsn <= lsn)
        {
            /*
             * We have to write the changed xmin to disk *before* we change
             * the in-memory value, otherwise after a crash we wouldn't know
             * that some catalog tuples might have been removed already.
             *
             * Ensure that by first writing to ->xmin and only update
             * ->effective_xmin once the new state is synced to disk. After a
             * crash ->effective_xmin is set to ->xmin.
             */
            if (TransactionIdIsValid(MyReplicationSlot->candidate_catalog_xmin) &&
                MyReplicationSlot->data.catalog_xmin != MyReplicationSlot->candidate_catalog_xmin)
            {
                MyReplicationSlot->data.catalog_xmin = MyReplicationSlot->candidate_catalog_xmin;
                MyReplicationSlot->candidate_catalog_xmin = InvalidTransactionId;
                MyReplicationSlot->candidate_xmin_lsn = InvalidXLogRecPtr;
                updated_xmin = true;
            }
        }
 
        if (MyReplicationSlot->candidate_restart_valid != InvalidXLogRecPtr &&
            MyReplicationSlot->candidate_restart_valid <= lsn)
        {
            Assert(MyReplicationSlot->candidate_restart_lsn != InvalidXLogRecPtr);
 
            MyReplicationSlot->data.restart_lsn = MyReplicationSlot->candidate_restart_lsn;
            MyReplicationSlot->candidate_restart_lsn = InvalidXLogRecPtr;
            MyReplicationSlot->candidate_restart_valid = InvalidXLogRecPtr;
            updated_restart = true;
        }
 
        SpinLockRelease(&MyReplicationSlot->mutex);
 
        /* first write new xmin to disk, so we know what's up after a crash */
        if (updated_xmin || updated_restart)
        {
            ReplicationSlotMarkDirty();
            ReplicationSlotSave();
            elog(DEBUG1, "updated xmin: %u restart: %u", updated_xmin, updated_restart);
        }
 
        /*
         * Now the new xmin is safely on disk, we can let the global value
         * advance. We do not take ProcArrayLock or similar since we only
         * advance xmin here and there's not much harm done by a concurrent
         * computation missing that.
         */
        if (updated_xmin)
        {
            SpinLockAcquire(&MyReplicationSlot->mutex);
            MyReplicationSlot->effective_catalog_xmin = MyReplicationSlot->data.catalog_xmin;
            SpinLockRelease(&MyReplicationSlot->mutex);
 
            ReplicationSlotsComputeRequiredXmin(false);
            ReplicationSlotsComputeRequiredLSN();
        }
    }
    else
    {
        SpinLockAcquire(&MyReplicationSlot->mutex);
 
        /*
         * Prevent moving the confirmed_flush backwards. See comments above
         * for the details.
         */
        if (lsn > MyReplicationSlot->data.confirmed_flush)
            MyReplicationSlot->data.confirmed_flush = lsn;
 
        SpinLockRelease(&MyReplicationSlot->mutex);
    }
}

References Assert(), ReplicationSlot::candidate_catalog_xmin, ReplicationSlot::candidate_restart_lsn, ReplicationSlot::candidate_restart_valid, ReplicationSlot::candidate_xmin_lsn, ReplicationSlotPersistentData::catalog_xmin, ReplicationSlotPersistentData::confirmed_flush, ReplicationSlot::data, DEBUG1, ReplicationSlot::effective_catalog_xmin, elog, InvalidTransactionId, InvalidXLogRecPtr, ReplicationSlot::mutex, MyReplicationSlot, ReplicationSlotMarkDirty(), ReplicationSlotSave(), ReplicationSlotsComputeRequiredLSN(), ReplicationSlotsComputeRequiredXmin(), ReplicationSlotPersistentData::restart_lsn, SpinLockAcquire, SpinLockRelease, and TransactionIdIsValid.

Referenced by LogicalIncreaseRestartDecodingForSlot(), LogicalIncreaseXminForSlot(), LogicalSlotAdvanceAndCheckSnapState(), pg_logical_slot_get_changes_guts(), and ProcessStandbyReplyMessage().

LogicalIncreaseRestartDecodingForSlot()

void LogicalIncreaseRestartDecodingForSlot	(	XLogRecPtr	current_lsn,
		XLogRecPtr	restart_lsn
	)

Definition at line 1742 of file logical.c.

{
    bool        updated_lsn = false;
    ReplicationSlot *slot;
 
    slot = MyReplicationSlot;
 
    Assert(slot != NULL);
    Assert(restart_lsn != InvalidXLogRecPtr);
    Assert(current_lsn != InvalidXLogRecPtr);
 
    SpinLockAcquire(&slot->mutex);
 
    /* don't overwrite if have a newer restart lsn */
    if (restart_lsn <= slot->data.restart_lsn)
    {
        SpinLockRelease(&slot->mutex);
    }
 
    /*
     * We might have already flushed far enough to directly accept this lsn,
     * in this case there is no need to check for existing candidate LSNs
     */
    else if (current_lsn <= slot->data.confirmed_flush)
    {
        slot->candidate_restart_valid = current_lsn;
        slot->candidate_restart_lsn = restart_lsn;
        SpinLockRelease(&slot->mutex);
 
        /* our candidate can directly be used */
        updated_lsn = true;
    }
 
    /*
     * Only increase if the previous values have been applied, otherwise we
     * might never end up updating if the receiver acks too slowly. A missed
     * value here will just cause some extra effort after reconnecting.
     */
    else if (slot->candidate_restart_valid == InvalidXLogRecPtr)
    {
        slot->candidate_restart_valid = current_lsn;
        slot->candidate_restart_lsn = restart_lsn;
        SpinLockRelease(&slot->mutex);
 
        elog(DEBUG1, "got new restart lsn %X/%X at %X/%X",
             LSN_FORMAT_ARGS(restart_lsn),
             LSN_FORMAT_ARGS(current_lsn));
    }
    else
    {
        XLogRecPtr  candidate_restart_lsn;
        XLogRecPtr  candidate_restart_valid;
        XLogRecPtr  confirmed_flush;
 
        candidate_restart_lsn = slot->candidate_restart_lsn;
        candidate_restart_valid = slot->candidate_restart_valid;
        confirmed_flush = slot->data.confirmed_flush;
        SpinLockRelease(&slot->mutex);
 
        elog(DEBUG1, "failed to increase restart lsn: proposed %X/%X, after %X/%X, current candidate %X/%X, current after %X/%X, flushed up to %X/%X",
             LSN_FORMAT_ARGS(restart_lsn),
             LSN_FORMAT_ARGS(current_lsn),
             LSN_FORMAT_ARGS(candidate_restart_lsn),
             LSN_FORMAT_ARGS(candidate_restart_valid),
             LSN_FORMAT_ARGS(confirmed_flush));
    }
 
    /* candidates are already valid with the current flush position, apply */
    if (updated_lsn)
        LogicalConfirmReceivedLocation(slot->data.confirmed_flush);
}

References Assert(), ReplicationSlot::candidate_restart_lsn, ReplicationSlot::candidate_restart_valid, ReplicationSlotPersistentData::confirmed_flush, ReplicationSlot::data, data, DEBUG1, elog, InvalidXLogRecPtr, LogicalConfirmReceivedLocation(), LSN_FORMAT_ARGS, ReplicationSlot::mutex, MyReplicationSlot, SpinLockAcquire, and SpinLockRelease.

Referenced by SnapBuildProcessRunningXacts().

LogicalIncreaseXminForSlot()

void LogicalIncreaseXminForSlot	(	XLogRecPtr	current_lsn,
		TransactionId	xmin
	)

Definition at line 1674 of file logical.c.

{
    bool        updated_xmin = false;
    ReplicationSlot *slot;
    bool        got_new_xmin = false;
 
    slot = MyReplicationSlot;
 
    Assert(slot != NULL);
 
    SpinLockAcquire(&slot->mutex);
 
    /*
     * don't overwrite if we already have a newer xmin. This can happen if we
     * restart decoding in a slot.
     */
    if (TransactionIdPrecedesOrEquals(xmin, slot->data.catalog_xmin))
    {
    }
 
    /*
     * If the client has already confirmed up to this lsn, we directly can
     * mark this as accepted. This can happen if we restart decoding in a
     * slot.
     */
    else if (current_lsn <= slot->data.confirmed_flush)
    {
        slot->candidate_catalog_xmin = xmin;
        slot->candidate_xmin_lsn = current_lsn;
 
        /* our candidate can directly be used */
        updated_xmin = true;
    }
 
    /*
     * Only increase if the previous values have been applied, otherwise we
     * might never end up updating if the receiver acks too slowly.
     */
    else if (slot->candidate_xmin_lsn == InvalidXLogRecPtr)
    {
        slot->candidate_catalog_xmin = xmin;
        slot->candidate_xmin_lsn = current_lsn;
 
        /*
         * Log new xmin at an appropriate log level after releasing the
         * spinlock.
         */
        got_new_xmin = true;
    }
    SpinLockRelease(&slot->mutex);
 
    if (got_new_xmin)
        elog(DEBUG1, "got new catalog xmin %u at %X/%X", xmin,
             LSN_FORMAT_ARGS(current_lsn));
 
    /* candidate already valid with the current flush position, apply */
    if (updated_xmin)
        LogicalConfirmReceivedLocation(slot->data.confirmed_flush);
}

References Assert(), ReplicationSlot::candidate_catalog_xmin, ReplicationSlot::candidate_xmin_lsn, ReplicationSlotPersistentData::catalog_xmin, ReplicationSlotPersistentData::confirmed_flush, ReplicationSlot::data, data, DEBUG1, elog, InvalidXLogRecPtr, LogicalConfirmReceivedLocation(), LSN_FORMAT_ARGS, ReplicationSlot::mutex, MyReplicationSlot, SpinLockAcquire, SpinLockRelease, and TransactionIdPrecedesOrEquals().

Referenced by SnapBuildProcessRunningXacts().

LogicalReplicationSlotHasPendingWal()

bool LogicalReplicationSlotHasPendingWal

(

XLogRecPtr

end_of_wal

)

Definition at line 1981 of file logical.c.

{
    bool        has_pending_wal = false;
 
    Assert(MyReplicationSlot);
 
    PG_TRY();
    {
        LogicalDecodingContext *ctx;
 
        /*
         * Create our decoding context in fast_forward mode, passing start_lsn
         * as InvalidXLogRecPtr, so that we start processing from the slot's
         * confirmed_flush.
         */
        ctx = CreateDecodingContext(InvalidXLogRecPtr,
                                    NIL,
                                    true,   /* fast_forward */
                                    XL_ROUTINE(.page_read = read_local_xlog_page,
                                               .segment_open = wal_segment_open,
                                               .segment_close = wal_segment_close),
                                    NULL, NULL, NULL);
 
        /*
         * Start reading at the slot's restart_lsn, which we know points to a
         * valid record.
         */
        XLogBeginRead(ctx->reader, MyReplicationSlot->data.restart_lsn);
 
        /* Invalidate non-timetravel entries */
        InvalidateSystemCaches();
 
        /* Loop until the end of WAL or some changes are processed */
        while (!has_pending_wal && ctx->reader->EndRecPtr < end_of_wal)
        {
            XLogRecord *record;
            char       *errm = NULL;
 
            record = XLogReadRecord(ctx->reader, &errm);
 
            if (errm)
                elog(ERROR, "could not find record for logical decoding: %s", errm);
 
            if (record != NULL)
                LogicalDecodingProcessRecord(ctx, ctx->reader);
 
            has_pending_wal = ctx->processing_required;
 
            CHECK_FOR_INTERRUPTS();
        }
 
        /* Clean up */
        FreeDecodingContext(ctx);
        InvalidateSystemCaches();
    }
    PG_CATCH();
    {
        /* clear all timetravel entries */
        InvalidateSystemCaches();
 
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    return has_pending_wal;
}

References Assert(), CHECK_FOR_INTERRUPTS, CreateDecodingContext(), ReplicationSlot::data, elog, XLogReaderState::EndRecPtr, ERROR, FreeDecodingContext(), InvalidateSystemCaches(), InvalidXLogRecPtr, LogicalDecodingProcessRecord(), MyReplicationSlot, NIL, PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, LogicalDecodingContext::processing_required, read_local_xlog_page(), LogicalDecodingContext::reader, ReplicationSlotPersistentData::restart_lsn, wal_segment_close(), wal_segment_open(), XL_ROUTINE, XLogBeginRead(), and XLogReadRecord().

Referenced by binary_upgrade_logical_slot_has_caught_up().

LogicalSlotAdvanceAndCheckSnapState()

XLogRecPtr LogicalSlotAdvanceAndCheckSnapState	(	XLogRecPtr	moveto,
		bool *	found_consistent_snapshot
	)

Definition at line 2063 of file logical.c.

{
    LogicalDecodingContext *ctx;
    ResourceOwner old_resowner = CurrentResourceOwner;
    XLogRecPtr  retlsn;
 
    Assert(moveto != InvalidXLogRecPtr);
 
    if (found_consistent_snapshot)
        *found_consistent_snapshot = false;
 
    PG_TRY();
    {
        /*
         * Create our decoding context in fast_forward mode, passing start_lsn
         * as InvalidXLogRecPtr, so that we start processing from my slot's
         * confirmed_flush.
         */
        ctx = CreateDecodingContext(InvalidXLogRecPtr,
                                    NIL,
                                    true,   /* fast_forward */
                                    XL_ROUTINE(.page_read = read_local_xlog_page,
                                               .segment_open = wal_segment_open,
                                               .segment_close = wal_segment_close),
                                    NULL, NULL, NULL);
 
        /*
         * Wait for specified streaming replication standby servers (if any)
         * to confirm receipt of WAL up to moveto lsn.
         */
        WaitForStandbyConfirmation(moveto);
 
        /*
         * Start reading at the slot's restart_lsn, which we know to point to
         * a valid record.
         */
        XLogBeginRead(ctx->reader, MyReplicationSlot->data.restart_lsn);
 
        /* invalidate non-timetravel entries */
        InvalidateSystemCaches();
 
        /* Decode records until we reach the requested target */
        while (ctx->reader->EndRecPtr < moveto)
        {
            char       *errm = NULL;
            XLogRecord *record;
 
            /*
             * Read records.  No changes are generated in fast_forward mode,
             * but snapbuilder/slot statuses are updated properly.
             */
            record = XLogReadRecord(ctx->reader, &errm);
            if (errm)
                elog(ERROR, "could not find record while advancing replication slot: %s",
                     errm);
 
            /*
             * Process the record.  Storage-level changes are ignored in
             * fast_forward mode, but other modules (such as snapbuilder)
             * might still have critical updates to do.
             */
            if (record)
                LogicalDecodingProcessRecord(ctx, ctx->reader);
 
            CHECK_FOR_INTERRUPTS();
        }
 
        if (found_consistent_snapshot && DecodingContextReady(ctx))
            *found_consistent_snapshot = true;
 
        /*
         * Logical decoding could have clobbered CurrentResourceOwner during
         * transaction management, so restore the executor's value.  (This is
         * a kluge, but it's not worth cleaning up right now.)
         */
        CurrentResourceOwner = old_resowner;
 
        if (ctx->reader->EndRecPtr != InvalidXLogRecPtr)
        {
            LogicalConfirmReceivedLocation(moveto);
 
            /*
             * If only the confirmed_flush LSN has changed the slot won't get
             * marked as dirty by the above. Callers on the walsender
             * interface are expected to keep track of their own progress and
             * don't need it written out. But SQL-interface users cannot
             * specify their own start positions and it's harder for them to
             * keep track of their progress, so we should make more of an
             * effort to save it for them.
             *
             * Dirty the slot so it is written out at the next checkpoint. The
             * LSN position advanced to may still be lost on a crash but this
             * makes the data consistent after a clean shutdown.
             */
            ReplicationSlotMarkDirty();
        }
 
        retlsn = MyReplicationSlot->data.confirmed_flush;
 
        /* free context, call shutdown callback */
        FreeDecodingContext(ctx);
 
        InvalidateSystemCaches();
    }
    PG_CATCH();
    {
        /* clear all timetravel entries */
        InvalidateSystemCaches();
 
        PG_RE_THROW();
    }
    PG_END_TRY();
 
    return retlsn;
}

References Assert(), CHECK_FOR_INTERRUPTS, ReplicationSlotPersistentData::confirmed_flush, CreateDecodingContext(), CurrentResourceOwner, ReplicationSlot::data, DecodingContextReady(), elog, XLogReaderState::EndRecPtr, ERROR, FreeDecodingContext(), InvalidateSystemCaches(), InvalidXLogRecPtr, LogicalConfirmReceivedLocation(), LogicalDecodingProcessRecord(), MyReplicationSlot, NIL, PG_CATCH, PG_END_TRY, PG_RE_THROW, PG_TRY, read_local_xlog_page(), LogicalDecodingContext::reader, ReplicationSlotMarkDirty(), ReplicationSlotPersistentData::restart_lsn, WaitForStandbyConfirmation(), wal_segment_close(), wal_segment_open(), XL_ROUTINE, XLogBeginRead(), and XLogReadRecord().

Referenced by pg_logical_replication_slot_advance(), and update_local_synced_slot().

ResetLogicalStreamingState()

void ResetLogicalStreamingState

(

void

)

Definition at line 1924 of file logical.c.

{
    CheckXidAlive = InvalidTransactionId;
    bsysscan = false;
}

References bsysscan, CheckXidAlive, and InvalidTransactionId.

Referenced by AbortSubTransaction(), and AbortTransaction().

UpdateDecodingStats()

void UpdateDecodingStats

(

LogicalDecodingContext *

ctx

)

Definition at line 1934 of file logical.c.

{
    ReorderBuffer *rb = ctx->reorder;
    PgStat_StatReplSlotEntry repSlotStat;
 
    /* Nothing to do if we don't have any replication stats to be sent. */
    if (rb->spillBytes <= 0 && rb->streamBytes <= 0 && rb->totalBytes <= 0)
        return;
 
    elog(DEBUG2, "UpdateDecodingStats: updating stats %p %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64 " %" PRId64,
         rb,
         rb->spillTxns,
         rb->spillCount,
         rb->spillBytes,
         rb->streamTxns,
         rb->streamCount,
         rb->streamBytes,
         rb->totalTxns,
         rb->totalBytes);
 
    repSlotStat.spill_txns = rb->spillTxns;
    repSlotStat.spill_count = rb->spillCount;
    repSlotStat.spill_bytes = rb->spillBytes;
    repSlotStat.stream_txns = rb->streamTxns;
    repSlotStat.stream_count = rb->streamCount;
    repSlotStat.stream_bytes = rb->streamBytes;
    repSlotStat.total_txns = rb->totalTxns;
    repSlotStat.total_bytes = rb->totalBytes;
 
    pgstat_report_replslot(ctx->slot, &repSlotStat);
 
    rb->spillTxns = 0;
    rb->spillCount = 0;
    rb->spillBytes = 0;
    rb->streamTxns = 0;
    rb->streamCount = 0;
    rb->streamBytes = 0;
    rb->totalTxns = 0;
    rb->totalBytes = 0;
}

References DEBUG2, elog, pgstat_report_replslot(), LogicalDecodingContext::reorder, LogicalDecodingContext::slot, PgStat_StatReplSlotEntry::spill_bytes, PgStat_StatReplSlotEntry::spill_count, PgStat_StatReplSlotEntry::spill_txns, ReorderBuffer::spillBytes, ReorderBuffer::spillCount, ReorderBuffer::spillTxns, PgStat_StatReplSlotEntry::stream_bytes, PgStat_StatReplSlotEntry::stream_count, PgStat_StatReplSlotEntry::stream_txns, ReorderBuffer::streamBytes, ReorderBuffer::streamCount, ReorderBuffer::streamTxns, PgStat_StatReplSlotEntry::total_bytes, PgStat_StatReplSlotEntry::total_txns, ReorderBuffer::totalBytes, and ReorderBuffer::totalTxns.

Referenced by DecodeAbort(), DecodeCommit(), DecodePrepare(), ReorderBufferSerializeTXN(), and ReorderBufferStreamTXN().