tcn.c File Reference

#include "postgres.h"
#include "access/htup_details.h"
#include "commands/async.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "lib/stringinfo.h"
#include "utils/rel.h"
#include "utils/syscache.h"

Include dependency graph for tcn.c:

Go to the source code of this file.

Functions
static void	strcpy_quoted (StringInfo r, const char *s, const char q)
	PG_FUNCTION_INFO_V1 (triggered_change_notification)
Datum	triggered_change_notification (PG_FUNCTION_ARGS)

Variables
	PG_MODULE_MAGIC

Function Documentation

PG_FUNCTION_INFO_V1()

PG_FUNCTION_INFO_V1

(

triggered_change_notification

)

strcpy_quoted()

static void strcpy_quoted ( StringInfo  r, const char *  s, const char  q  )

static

Definition at line 33 of file tcn.c.

{
    appendStringInfoCharMacro(r, q);
    while (*s)
    {
        if (*s == q)
            appendStringInfoCharMacro(r, q);
        appendStringInfoCharMacro(r, *s);
        s++;
    }
    appendStringInfoCharMacro(r, q);
}

References appendStringInfoCharMacro.

Referenced by triggered_change_notification().

triggered_change_notification()

Datum triggered_change_notification

(

PG_FUNCTION_ARGS

)

Definition at line 56 of file tcn.c.

{
    TriggerData *trigdata = (TriggerData *) fcinfo->context;
    Trigger    *trigger;
    int         nargs;
    HeapTuple   trigtuple;
    Relation    rel;
    TupleDesc   tupdesc;
    char       *channel;
    char        operation;
    StringInfo  payload = makeStringInfo();
    bool        foundPK;
 
    List       *indexoidlist;
    ListCell   *indexoidscan;
 
    /* make sure it's called as a trigger */
    if (!CALLED_AS_TRIGGER(fcinfo))
        ereport(ERROR,
                (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                 errmsg("triggered_change_notification: must be called as trigger")));
 
    /* and that it's called after the change */
    if (!TRIGGER_FIRED_AFTER(trigdata->tg_event))
        ereport(ERROR,
                (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                 errmsg("triggered_change_notification: must be called after the change")));
 
    /* and that it's called for each row */
    if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
        ereport(ERROR,
                (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                 errmsg("triggered_change_notification: must be called for each row")));
 
    if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
        operation = 'I';
    else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
        operation = 'U';
    else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
        operation = 'D';
    else
    {
        elog(ERROR, "triggered_change_notification: trigger fired by unrecognized operation");
        operation = 'X';        /* silence compiler warning */
    }
 
    trigger = trigdata->tg_trigger;
    nargs = trigger->tgnargs;
    if (nargs > 1)
        ereport(ERROR,
                (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                 errmsg("triggered_change_notification: must not be called with more than one parameter")));
 
    if (nargs == 0)
        channel = "tcn";
    else
        channel = trigger->tgargs[0];
 
    /* get tuple data */
    trigtuple = trigdata->tg_trigtuple;
    rel = trigdata->tg_relation;
    tupdesc = rel->rd_att;
 
    foundPK = false;
 
    /*
     * Get the list of index OIDs for the table from the relcache, and look up
     * each one in the pg_index syscache until we find one marked primary key
     * (hopefully there isn't more than one such).
     */
    indexoidlist = RelationGetIndexList(rel);
 
    foreach(indexoidscan, indexoidlist)
    {
        Oid         indexoid = lfirst_oid(indexoidscan);
        HeapTuple   indexTuple;
        Form_pg_index index;
 
        indexTuple = SearchSysCache1(INDEXRELID, ObjectIdGetDatum(indexoid));
        if (!HeapTupleIsValid(indexTuple))  /* should not happen */
            elog(ERROR, "cache lookup failed for index %u", indexoid);
        index = (Form_pg_index) GETSTRUCT(indexTuple);
        /* we're only interested if it is the primary key and valid */
        if (index->indisprimary && index->indisvalid)
        {
            int         indnkeyatts = index->indnkeyatts;
 
            if (indnkeyatts > 0)
            {
                int         i;
 
                foundPK = true;
 
                strcpy_quoted(payload, RelationGetRelationName(rel), '"');
                appendStringInfoCharMacro(payload, ',');
                appendStringInfoCharMacro(payload, operation);
 
                for (i = 0; i < indnkeyatts; i++)
                {
                    int         colno = index->indkey.values[i];
                    Form_pg_attribute attr = TupleDescAttr(tupdesc, colno - 1);
 
                    appendStringInfoCharMacro(payload, ',');
                    strcpy_quoted(payload, NameStr(attr->attname), '"');
                    appendStringInfoCharMacro(payload, '=');
                    strcpy_quoted(payload, SPI_getvalue(trigtuple, tupdesc, colno), '\'');
                }
 
                Async_Notify(channel, payload->data);
            }
            ReleaseSysCache(indexTuple);
            break;
        }
        ReleaseSysCache(indexTuple);
    }
 
    list_free(indexoidlist);
 
    if (!foundPK)
        ereport(ERROR,
                (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                 errmsg("triggered_change_notification: must be called on a table with a primary key")));
 
    return PointerGetDatum(NULL);   /* after trigger; value doesn't matter */
}

References appendStringInfoCharMacro, Async_Notify(), CALLED_AS_TRIGGER, elog, ereport, errcode(), errmsg(), ERROR, GETSTRUCT(), HeapTupleIsValid, i, lfirst_oid, list_free(), makeStringInfo(), NameStr, ObjectIdGetDatum(), PointerGetDatum(), RelationData::rd_att, RelationGetIndexList(), RelationGetRelationName, ReleaseSysCache(), SearchSysCache1(), SPI_getvalue(), strcpy_quoted(), TriggerData::tg_event, TriggerData::tg_relation, TriggerData::tg_trigger, TriggerData::tg_trigtuple, Trigger::tgnargs, TRIGGER_FIRED_AFTER, TRIGGER_FIRED_BY_DELETE, TRIGGER_FIRED_BY_INSERT, TRIGGER_FIRED_BY_UPDATE, TRIGGER_FIRED_FOR_ROW, and TupleDescAttr().

Variable Documentation

PG_MODULE_MAGIC

PG_MODULE_MAGIC

Definition at line 26 of file tcn.c.