extendplan.c

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/*-------------------------------------------------------------------------
 *
 * extendplan.c
 *    Extend core planner objects with additional private state
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994-5, Regents of the University of California
 *
 * The interfaces defined in this file make it possible for loadable
 * modules to store their own private state inside of key planner data
 * structures -- specifically, the PlannerGlobal, PlannerInfo, and
 * RelOptInfo structures. This can make it much easier to write
 * reasonably efficient planner extensions; for instance, code that
 * uses set_join_pathlist_hook can arrange to compute a key intermediate
 * result once per joinrel rather than on every call.
 *
 * IDENTIFICATION
 *    src/backend/optimizer/util/extendplan.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "optimizer/extendplan.h"
#include "port/pg_bitutils.h"
#include "utils/memutils.h"
 
static const char **PlannerExtensionNameArray = NULL;
static int  PlannerExtensionNamesAssigned = 0;
static int  PlannerExtensionNamesAllocated = 0;
 
/*
 * Map the name of a planner extension to an integer ID.
 *
 * Within the lifetime of a particular backend, the same name will be mapped
 * to the same ID every time. IDs are not stable across backends. Use the ID
 * that you get from this function to call the remaining functions in this
 * file.
 */
int
GetPlannerExtensionId(const char *extension_name)
{
    /* Search for an existing extension by this name; if found, return ID. */
    for (int i = 0; i < PlannerExtensionNamesAssigned; ++i)
        if (strcmp(PlannerExtensionNameArray[i], extension_name) == 0)
            return i;
 
    /* If there is no array yet, create one. */
    if (PlannerExtensionNameArray == NULL)
    {
        PlannerExtensionNamesAllocated = 16;
        PlannerExtensionNameArray = (const char **)
            MemoryContextAlloc(TopMemoryContext,
                               PlannerExtensionNamesAllocated
                               * sizeof(char *));
    }
 
    /* If there's an array but it's currently full, expand it. */
    if (PlannerExtensionNamesAssigned >= PlannerExtensionNamesAllocated)
    {
        int         i = pg_nextpower2_32(PlannerExtensionNamesAssigned + 1);
 
        PlannerExtensionNameArray = (const char **)
            repalloc(PlannerExtensionNameArray, i * sizeof(char *));
        PlannerExtensionNamesAllocated = i;
    }
 
    /* Assign and return new ID. */
    PlannerExtensionNameArray[PlannerExtensionNamesAssigned] = extension_name;
    return PlannerExtensionNamesAssigned++;
}
 
/*
 * Store extension-specific state into a PlannerGlobal.
 */
void
SetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id,
                               void *opaque)
{
    Assert(extension_id >= 0);
 
    /* If there is no array yet, create one. */
    if (glob->extension_state == NULL)
    {
        MemoryContext planner_cxt;
        Size        sz;
 
        planner_cxt = GetMemoryChunkContext(glob);
        glob->extension_state_allocated =
            Max(4, pg_nextpower2_32(extension_id + 1));
        sz = glob->extension_state_allocated * sizeof(void *);
        glob->extension_state = MemoryContextAllocZero(planner_cxt, sz);
    }
 
    /* If there's an array but it's currently full, expand it. */
    if (extension_id >= glob->extension_state_allocated)
    {
        int         i;
 
        i = pg_nextpower2_32(extension_id + 1);
        glob->extension_state = repalloc0_array(glob->extension_state, void *,
                                                glob->extension_state_allocated, i);
        glob->extension_state_allocated = i;
    }
 
    glob->extension_state[extension_id] = opaque;
}
 
/*
 * Store extension-specific state into a PlannerInfo.
 */
void
SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
                             void *opaque)
{
    Assert(extension_id >= 0);
 
    /* If there is no array yet, create one. */
    if (root->extension_state == NULL)
    {
        Size        sz;
 
        root->extension_state_allocated =
            Max(4, pg_nextpower2_32(extension_id + 1));
        sz = root->extension_state_allocated * sizeof(void *);
        root->extension_state = MemoryContextAllocZero(root->planner_cxt, sz);
    }
 
    /* If there's an array but it's currently full, expand it. */
    if (extension_id >= root->extension_state_allocated)
    {
        int         i;
 
        i = pg_nextpower2_32(extension_id + 1);
        root->extension_state = repalloc0_array(root->extension_state, void *,
                                                root->extension_state_allocated, i);
        root->extension_state_allocated = i;
    }
 
    root->extension_state[extension_id] = opaque;
}
 
/*
 * Store extension-specific state into a RelOptInfo.
 */
void
SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
                            void *opaque)
{
    Assert(extension_id >= 0);
 
    /* If there is no array yet, create one. */
    if (rel->extension_state == NULL)
    {
        MemoryContext planner_cxt;
        Size        sz;
 
        planner_cxt = GetMemoryChunkContext(rel);
        rel->extension_state_allocated =
            Max(4, pg_nextpower2_32(extension_id + 1));
        sz = rel->extension_state_allocated * sizeof(void *);
        rel->extension_state = MemoryContextAllocZero(planner_cxt, sz);
    }
 
    /* If there's an array but it's currently full, expand it. */
    if (extension_id >= rel->extension_state_allocated)
    {
        int         i;
 
        i = pg_nextpower2_32(extension_id + 1);
        rel->extension_state = repalloc0_array(rel->extension_state, void *,
                                               rel->extension_state_allocated, i);
        rel->extension_state_allocated = i;
    }
 
    rel->extension_state[extension_id] = opaque;
}