greenplumn autoprewarm 源码
greenplumn autoprewarm 代码
文件路径：/contrib/pg_prewarm/autoprewarm.c
/*-------------------------------------------------------------------------
*
* autoprewarm.c
* Periodically dump information about the blocks present in
* shared_buffers, and reload them on server restart.
*
* Due to locking considerations, we can't actually begin prewarming
* until the server reaches a consistent state. We need the catalogs
* to be consistent so that we can figure out which relation to lock,
* and we need to lock the relations so that we don't try to prewarm
* pages from a relation that is in the process of being dropped.
*
* While prewarming, autoprewarm will use two workers. There's a
* master worker that reads and sorts the list of blocks to be
* prewarmed and then launches a per-database worker for each
* relevant database in turn. The former keeps running after the
* initial prewarm is complete to update the dump file periodically.
*
* Copyright (c) 2016-2019, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/pg_prewarm/autoprewarm.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <unistd.h>
#include "access/relation.h"
#include "access/xact.h"
#include "catalog/pg_class.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/bgworker.h"
#include "storage/buf_internals.h"
#include "storage/dsm.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/lwlock.h"
#include "storage/proc.h"
#include "storage/procsignal.h"
#include "storage/shmem.h"
#include "storage/smgr.h"
#include "tcop/tcopprot.h"
#include "utils/acl.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/relfilenodemap.h"
#include "utils/resowner.h"
#define AUTOPREWARM_FILE "autoprewarm.blocks"
/* Metadata for each block we dump. */
typedef struct BlockInfoRecord
{
Oid database;
Oid tablespace;
Oid filenode;
ForkNumber forknum;
BlockNumber blocknum;
} BlockInfoRecord;
/* Shared state information for autoprewarm bgworker. */
typedef struct AutoPrewarmSharedState
{
LWLock lock; /* mutual exclusion */
pid_t bgworker_pid; /* for main bgworker */
pid_t pid_using_dumpfile; /* for autoprewarm or block dump */
/* Following items are for communication with per-database worker */
dsm_handle block_info_handle;
Oid database;
int prewarm_start_idx;
int prewarm_stop_idx;
int prewarmed_blocks;
} AutoPrewarmSharedState;
void _PG_init(void);
void autoprewarm_main(Datum main_arg);
void autoprewarm_database_main(Datum main_arg);
PG_FUNCTION_INFO_V1(autoprewarm_start_worker);
PG_FUNCTION_INFO_V1(autoprewarm_dump_now);
static void apw_load_buffers(void);
static int apw_dump_now(bool is_bgworker, bool dump_unlogged);
static void apw_start_master_worker(void);
static void apw_start_database_worker(void);
static bool apw_init_shmem(void);
static void apw_detach_shmem(int code, Datum arg);
static int apw_compare_blockinfo(const void *p, const void *q);
static void apw_sigterm_handler(SIGNAL_ARGS);
static void apw_sighup_handler(SIGNAL_ARGS);
/* Flags set by signal handlers */
static volatile sig_atomic_t got_sigterm = false;
static volatile sig_atomic_t got_sighup = false;
/* Pointer to shared-memory state. */
static AutoPrewarmSharedState *apw_state = NULL;
/* GUC variables. */
static bool autoprewarm = true; /* start worker? */
static int autoprewarm_interval; /* dump interval */
/*
* Module load callback.
*/
void
_PG_init(void)
{
DefineCustomIntVariable("pg_prewarm.autoprewarm_interval",
"Sets the interval between dumps of shared buffers",
"If set to zero, time-based dumping is disabled.",
&autoprewarm_interval,
300,
0, INT_MAX / 1000,
PGC_SIGHUP,
GUC_UNIT_S,
NULL,
NULL,
NULL);
if (!process_shared_preload_libraries_in_progress)
return;
/* can't define PGC_POSTMASTER variable after startup */
DefineCustomBoolVariable("pg_prewarm.autoprewarm",
"Starts the autoprewarm worker.",
NULL,
&autoprewarm,
true,
PGC_POSTMASTER,
0,
NULL,
NULL,
NULL);
EmitWarningsOnPlaceholders("pg_prewarm");
RequestAddinShmemSpace(MAXALIGN(sizeof(AutoPrewarmSharedState)));
/* Register autoprewarm worker, if enabled. */
if (autoprewarm)
apw_start_master_worker();
}
/*
* Main entry point for the master autoprewarm process. Per-database workers
* have a separate entry point.
*/
void
autoprewarm_main(Datum main_arg)
{
bool first_time = true;
TimestampTz last_dump_time = 0;
/* Establish signal handlers; once that's done, unblock signals. */
pqsignal(SIGTERM, apw_sigterm_handler);
pqsignal(SIGHUP, apw_sighup_handler);
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
BackgroundWorkerUnblockSignals();
/* Create (if necessary) and attach to our shared memory area. */
if (apw_init_shmem())
first_time = false;
/* Set on-detach hook so that our PID will be cleared on exit. */
on_shmem_exit(apw_detach_shmem, 0);
/*
* Store our PID in the shared memory area --- unless there's already
* another worker running, in which case just exit.
*/
LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
if (apw_state->bgworker_pid != InvalidPid)
{
LWLockRelease(&apw_state->lock);
ereport(LOG,
(errmsg("autoprewarm worker is already running under PID %lu",
(unsigned long) apw_state->bgworker_pid)));
return;
}
apw_state->bgworker_pid = MyProcPid;
LWLockRelease(&apw_state->lock);
/*
* Preload buffers from the dump file only if we just created the shared
* memory region. Otherwise, it's either already been done or shouldn't
* be done - e.g. because the old dump file has been overwritten since the
* server was started.
*
* There's not much point in performing a dump immediately after we finish
* preloading; so, if we do end up preloading, consider the last dump time
* to be equal to the current time.
*/
if (first_time)
{
apw_load_buffers();
last_dump_time = GetCurrentTimestamp();
}
/* Periodically dump buffers until terminated. */
while (!got_sigterm)
{
/* In case of a SIGHUP, just reload the configuration. */
if (got_sighup)
{
got_sighup = false;
ProcessConfigFile(PGC_SIGHUP);
}
if (autoprewarm_interval <= 0)
{
/* We're only dumping at shutdown, so just wait forever. */
(void) WaitLatch(&MyProc->procLatch,
WL_LATCH_SET | WL_EXIT_ON_PM_DEATH,
-1L,
PG_WAIT_EXTENSION);
}
else
{
long delay_in_ms = 0;
TimestampTz next_dump_time = 0;
long secs = 0;
int usecs = 0;
/* Compute the next dump time. */
next_dump_time =
TimestampTzPlusMilliseconds(last_dump_time,
autoprewarm_interval * 1000);
TimestampDifference(GetCurrentTimestamp(), next_dump_time,
&secs, &usecs);
delay_in_ms = secs + (usecs / 1000);
/* Perform a dump if it's time. */
if (delay_in_ms <= 0)
{
last_dump_time = GetCurrentTimestamp();
apw_dump_now(true, false);
continue;
}
/* Sleep until the next dump time. */
(void) WaitLatch(&MyProc->procLatch,
WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,
delay_in_ms,
PG_WAIT_EXTENSION);
}
/* Reset the latch, loop. */
ResetLatch(&MyProc->procLatch);
}
/*
* Dump one last time. We assume this is probably the result of a system
* shutdown, although it's possible that we've merely been terminated.
*/
apw_dump_now(true, true);
}
/*
* Read the dump file and launch per-database workers one at a time to
* prewarm the buffers found there.
*/
static void
apw_load_buffers(void)
{
FILE *file = NULL;
int num_elements,
i;
BlockInfoRecord *blkinfo;
dsm_segment *seg;
/*
* Skip the prewarm if the dump file is in use; otherwise, prevent any
* other process from writing it while we're using it.
*/
LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
if (apw_state->pid_using_dumpfile == InvalidPid)
apw_state->pid_using_dumpfile = MyProcPid;
else
{
LWLockRelease(&apw_state->lock);
ereport(LOG,
(errmsg("skipping prewarm because block dump file is being written by PID %lu",
(unsigned long) apw_state->pid_using_dumpfile)));
return;
}
LWLockRelease(&apw_state->lock);
/*
* Open the block dump file. Exit quietly if it doesn't exist, but report
* any other error.
*/
file = AllocateFile(AUTOPREWARM_FILE, "r");
if (!file)
{
if (errno == ENOENT)
{
LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
apw_state->pid_using_dumpfile = InvalidPid;
LWLockRelease(&apw_state->lock);
return; /* No file to load. */
}
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read file \"%s\": %m",
AUTOPREWARM_FILE)));
}
/* First line of the file is a record count. */
if (fscanf(file, "<<%d>>\n", &num_elements) != 1)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not read from file \"%s\": %m",
AUTOPREWARM_FILE)));
/* Allocate a dynamic shared memory segment to store the record data. */
seg = dsm_create(sizeof(BlockInfoRecord) * num_elements, 0);
blkinfo = (BlockInfoRecord *) dsm_segment_address(seg);
/* Read records, one per line. */
for (i = 0; i < num_elements; i++)
{
unsigned forknum;
if (fscanf(file, "%u,%u,%u,%u,%u\n", &blkinfo[i].database,
&blkinfo[i].tablespace, &blkinfo[i].filenode,
&forknum, &blkinfo[i].blocknum) != 5)
ereport(ERROR,
(errmsg("autoprewarm block dump file is corrupted at line %d",
i + 1)));
blkinfo[i].forknum = forknum;
}
FreeFile(file);
/* Sort the blocks to be loaded. */
pg_qsort(blkinfo, num_elements, sizeof(BlockInfoRecord),
apw_compare_blockinfo);
/* Populate shared memory state. */
apw_state->block_info_handle = dsm_segment_handle(seg);
apw_state->prewarm_start_idx = apw_state->prewarm_stop_idx = 0;
apw_state->prewarmed_blocks = 0;
/* Get the info position of the first block of the next database. */
while (apw_state->prewarm_start_idx < num_elements)
{
int j = apw_state->prewarm_start_idx;
Oid current_db = blkinfo[j].database;
/*
* Advance the prewarm_stop_idx to the first BlockInfoRecord that does
* not belong to this database.
*/
j++;
while (j < num_elements)
{
if (current_db != blkinfo[j].database)
{
/*
* Combine BlockInfoRecords for global objects with those of
* the database.
*/
if (current_db != InvalidOid)
break;
current_db = blkinfo[j].database;
}
j++;
}
/*
* If we reach this point with current_db == InvalidOid, then only
* BlockInfoRecords belonging to global objects exist. We can't
* prewarm without a database connection, so just bail out.
*/
if (current_db == InvalidOid)
break;
/* Configure stop point and database for next per-database worker. */
apw_state->prewarm_stop_idx = j;
apw_state->database = current_db;
Assert(apw_state->prewarm_start_idx < apw_state->prewarm_stop_idx);
/* If we've run out of free buffers, don't launch another worker. */
if (!have_free_buffer())
break;
/*
* Start a per-database worker to load blocks for this database; this
* function will return once the per-database worker exits.
*/
apw_start_database_worker();
/* Prepare for next database. */
apw_state->prewarm_start_idx = apw_state->prewarm_stop_idx;
}
/* Clean up. */
dsm_detach(seg);
LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
apw_state->block_info_handle = DSM_HANDLE_INVALID;
apw_state->pid_using_dumpfile = InvalidPid;
LWLockRelease(&apw_state->lock);
/* Report our success. */
ereport(LOG,
(errmsg("autoprewarm successfully prewarmed %d of %d previously-loaded blocks",
apw_state->prewarmed_blocks, num_elements)));
}
/*
* Prewarm all blocks for one database (and possibly also global objects, if
* those got grouped with this database).
*/
void
autoprewarm_database_main(Datum main_arg)
{
int pos;
BlockInfoRecord *block_info;
Relation rel = NULL;
BlockNumber nblocks = 0;
BlockInfoRecord *old_blk = NULL;
dsm_segment *seg;
/* Establish signal handlers; once that's done, unblock signals. */
pqsignal(SIGTERM, die);
BackgroundWorkerUnblockSignals();
/* Connect to correct database and get block information. */
apw_init_shmem();
seg = dsm_attach(apw_state->block_info_handle);
if (seg == NULL)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("could not map dynamic shared memory segment")));
BackgroundWorkerInitializeConnectionByOid(apw_state->database, InvalidOid, 0);
block_info = (BlockInfoRecord *) dsm_segment_address(seg);
pos = apw_state->prewarm_start_idx;
/*
* Loop until we run out of blocks to prewarm or until we run out of free
* buffers.
*/
while (pos < apw_state->prewarm_stop_idx && have_free_buffer())
{
BlockInfoRecord *blk = &block_info[pos++];
Buffer buf;
CHECK_FOR_INTERRUPTS();
/*
* Quit if we've reached records for another database. If previous
* blocks are of some global objects, then continue pre-warming.
*/
if (old_blk != NULL && old_blk->database != blk->database &&
old_blk->database != 0)
break;
/*
* As soon as we encounter a block of a new relation, close the old
* relation. Note that rel will be NULL if try_relation_open failed
* previously; in that case, there is nothing to close.
*/
if (old_blk != NULL && old_blk->filenode != blk->filenode &&
rel != NULL)
{
relation_close(rel, AccessShareLock);
rel = NULL;
CommitTransactionCommand();
}
/*
* Try to open each new relation, but only once, when we first
* encounter it. If it's been dropped, skip the associated blocks.
*/
if (old_blk == NULL || old_blk->filenode != blk->filenode)
{
Oid reloid;
Assert(rel == NULL);
StartTransactionCommand();
reloid = RelidByRelfilenode(blk->tablespace, blk->filenode);
if (OidIsValid(reloid))
rel = relation_open(reloid, AccessShareLock);
if (!rel)
CommitTransactionCommand();
}
if (!rel)
{
old_blk = blk;
continue;
}
/* Once per fork, check for fork existence and size. */
if (old_blk == NULL ||
old_blk->filenode != blk->filenode ||
old_blk->forknum != blk->forknum)
{
RelationOpenSmgr(rel);
/*
* smgrexists is not safe for illegal forknum, hence check whether
* the passed forknum is valid before using it in smgrexists.
*/
if (blk->forknum > InvalidForkNumber &&
blk->forknum <= MAX_FORKNUM &&
smgrexists(rel->rd_smgr, blk->forknum))
nblocks = RelationGetNumberOfBlocksInFork(rel, blk->forknum);
else
nblocks = 0;
}
/* Check whether blocknum is valid and within fork file size. */
if (blk->blocknum >= nblocks)
{
/* Move to next forknum. */
old_blk = blk;
continue;
}
/* Prewarm buffer. */
buf = ReadBufferExtended(rel, blk->forknum, blk->blocknum, RBM_NORMAL,
NULL);
if (BufferIsValid(buf))
{
apw_state->prewarmed_blocks++;
ReleaseBuffer(buf);
}
old_blk = blk;
}
dsm_detach(seg);
/* Release lock on previous relation. */
if (rel)
{
relation_close(rel, AccessShareLock);
CommitTransactionCommand();
}
}
/*
* Dump information on blocks in shared buffers. We use a text format here
* so that it's easy to understand and even change the file contents if
* necessary.
* Returns the number of blocks dumped.
*/
static int
apw_dump_now(bool is_bgworker, bool dump_unlogged)
{
int num_blocks;
int i;
int ret;
BlockInfoRecord *block_info_array;
BufferDesc *bufHdr;
FILE *file;
char transient_dump_file_path[MAXPGPATH];
pid_t pid;
LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
pid = apw_state->pid_using_dumpfile;
if (apw_state->pid_using_dumpfile == InvalidPid)
apw_state->pid_using_dumpfile = MyProcPid;
LWLockRelease(&apw_state->lock);
if (pid != InvalidPid)
{
if (!is_bgworker)
ereport(ERROR,
(errmsg("could not perform block dump because dump file is being used by PID %lu",
(unsigned long) apw_state->pid_using_dumpfile)));
ereport(LOG,
(errmsg("skipping block dump because it is already being performed by PID %lu",
(unsigned long) apw_state->pid_using_dumpfile)));
return 0;
}
block_info_array =
(BlockInfoRecord *) palloc(sizeof(BlockInfoRecord) * NBuffers);
for (num_blocks = 0, i = 0; i < NBuffers; i++)
{
uint32 buf_state;
CHECK_FOR_INTERRUPTS();
bufHdr = GetBufferDescriptor(i);
/* Lock each buffer header before inspecting. */
buf_state = LockBufHdr(bufHdr);
/*
* Unlogged tables will be automatically truncated after a crash or
* unclean shutdown. In such cases we need not prewarm them. Dump them
* only if requested by caller.
*/
if (buf_state & BM_TAG_VALID &&
((buf_state & BM_PERMANENT) || dump_unlogged))
{
block_info_array[num_blocks].database = bufHdr->tag.rnode.dbNode;
block_info_array[num_blocks].tablespace = bufHdr->tag.rnode.spcNode;
block_info_array[num_blocks].filenode = bufHdr->tag.rnode.relNode;
block_info_array[num_blocks].forknum = bufHdr->tag.forkNum;
block_info_array[num_blocks].blocknum = bufHdr->tag.blockNum;
++num_blocks;
}
UnlockBufHdr(bufHdr, buf_state);
}
snprintf(transient_dump_file_path, MAXPGPATH, "%s.tmp", AUTOPREWARM_FILE);
file = AllocateFile(transient_dump_file_path, "w");
if (!file)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not open file \"%s\": %m",
transient_dump_file_path)));
ret = fprintf(file, "<<%d>>\n", num_blocks);
if (ret < 0)
{
int save_errno = errno;
FreeFile(file);
unlink(transient_dump_file_path);
errno = save_errno;
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not write to file \"%s\": %m",
transient_dump_file_path)));
}
for (i = 0; i < num_blocks; i++)
{
CHECK_FOR_INTERRUPTS();
ret = fprintf(file, "%u,%u,%u,%u,%u\n",
block_info_array[i].database,
block_info_array[i].tablespace,
block_info_array[i].filenode,
(uint32) block_info_array[i].forknum,
block_info_array[i].blocknum);
if (ret < 0)
{
int save_errno = errno;
FreeFile(file);
unlink(transient_dump_file_path);
errno = save_errno;
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not write to file \"%s\": %m",
transient_dump_file_path)));
}
}
pfree(block_info_array);
/*
* Rename transient_dump_file_path to AUTOPREWARM_FILE to make things
* permanent.
*/
ret = FreeFile(file);
if (ret != 0)
{
int save_errno = errno;
unlink(transient_dump_file_path);
errno = save_errno;
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not close file \"%s\": %m",
transient_dump_file_path)));
}
(void) durable_rename(transient_dump_file_path, AUTOPREWARM_FILE, ERROR);
apw_state->pid_using_dumpfile = InvalidPid;
ereport(DEBUG1,
(errmsg("wrote block details for %d blocks", num_blocks)));
return num_blocks;
}
/*
* SQL-callable function to launch autoprewarm.
*/
Datum
autoprewarm_start_worker(PG_FUNCTION_ARGS)
{
pid_t pid;
if (!autoprewarm)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("autoprewarm is disabled")));
apw_init_shmem();
LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
pid = apw_state->bgworker_pid;
LWLockRelease(&apw_state->lock);
if (pid != InvalidPid)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("autoprewarm worker is already running under PID %lu",
(unsigned long) pid)));
apw_start_master_worker();
PG_RETURN_VOID();
}
/*
* SQL-callable function to perform an immediate block dump.
*
* Note: this is declared to return int8, as insurance against some
* very distant day when we might make NBuffers wider than int.
*/
Datum
autoprewarm_dump_now(PG_FUNCTION_ARGS)
{
int num_blocks;
apw_init_shmem();
PG_ENSURE_ERROR_CLEANUP(apw_detach_shmem, 0);
{
num_blocks = apw_dump_now(false, true);
}
PG_END_ENSURE_ERROR_CLEANUP(apw_detach_shmem, 0);
PG_RETURN_INT64((int64) num_blocks);
}
/*
* Allocate and initialize autoprewarm related shared memory, if not already
* done, and set up backend-local pointer to that state. Returns true if an
* existing shared memory segment was found.
*/
static bool
apw_init_shmem(void)
{
bool found;
LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE);
apw_state = ShmemInitStruct("autoprewarm",
sizeof(AutoPrewarmSharedState),
&found);
if (!found)
{
/* First time through ... */
LWLockInitialize(&apw_state->lock, LWLockNewTrancheId());
apw_state->bgworker_pid = InvalidPid;
apw_state->pid_using_dumpfile = InvalidPid;
}
LWLockRelease(AddinShmemInitLock);
LWLockRegisterTranche(apw_state->lock.tranche, "autoprewarm");
return found;
}
/*
* Clear our PID from autoprewarm shared state.
*/
static void
apw_detach_shmem(int code, Datum arg)
{
LWLockAcquire(&apw_state->lock, LW_EXCLUSIVE);
if (apw_state->pid_using_dumpfile == MyProcPid)
apw_state->pid_using_dumpfile = InvalidPid;
if (apw_state->bgworker_pid == MyProcPid)
apw_state->bgworker_pid = InvalidPid;
LWLockRelease(&apw_state->lock);
}
/*
* Start autoprewarm master worker process.
*/
static void
apw_start_master_worker(void)
{
BackgroundWorker worker;
BackgroundWorkerHandle *handle;
BgwHandleStatus status;
pid_t pid;
MemSet(&worker, 0, sizeof(BackgroundWorker));
worker.bgw_flags = BGWORKER_SHMEM_ACCESS;
worker.bgw_start_time = BgWorkerStart_ConsistentState;
strcpy(worker.bgw_library_name, "pg_prewarm");
strcpy(worker.bgw_function_name, "autoprewarm_main");
strcpy(worker.bgw_name, "autoprewarm master");
strcpy(worker.bgw_type, "autoprewarm master");
if (process_shared_preload_libraries_in_progress)
{
RegisterBackgroundWorker(&worker);
return;
}
/* must set notify PID to wait for startup */
worker.bgw_notify_pid = MyProcPid;
if (!RegisterDynamicBackgroundWorker(&worker, &handle))
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("could not register background process"),
errhint("You may need to increase max_worker_processes.")));
status = WaitForBackgroundWorkerStartup(handle, &pid);
if (status != BGWH_STARTED)
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("could not start background process"),
errhint("More details may be available in the server log.")));
}
/*
* Start autoprewarm per-database worker process.
*/
static void
apw_start_database_worker(void)
{
BackgroundWorker worker;
BackgroundWorkerHandle *handle;
MemSet(&worker, 0, sizeof(BackgroundWorker));
worker.bgw_flags =
BGWORKER_SHMEM_ACCESS | BGWORKER_BACKEND_DATABASE_CONNECTION;
worker.bgw_start_time = BgWorkerStart_ConsistentState;
worker.bgw_restart_time = BGW_NEVER_RESTART;
strcpy(worker.bgw_library_name, "pg_prewarm");
strcpy(worker.bgw_function_name, "autoprewarm_database_main");
strcpy(worker.bgw_name, "autoprewarm worker");
strcpy(worker.bgw_type, "autoprewarm worker");
/* must set notify PID to wait for shutdown */
worker.bgw_notify_pid = MyProcPid;
if (!RegisterDynamicBackgroundWorker(&worker, &handle))
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("registering dynamic bgworker autoprewarm failed"),
errhint("Consider increasing configuration parameter \"max_worker_processes\".")));
/*
* Ignore return value; if it fails, postmaster has died, but we have
* checks for that elsewhere.
*/
WaitForBackgroundWorkerShutdown(handle);
}
/* Compare member elements to check whether they are not equal. */
#define cmp_member_elem(fld) \
do { \
if (a->fld < b->fld) \
return -1; \
else if (a->fld > b->fld) \
return 1; \
} while(0)
/*
* apw_compare_blockinfo
*
* We depend on all records for a particular database being consecutive
* in the dump file; each per-database worker will preload blocks until
* it sees a block for some other database. Sorting by tablespace,
* filenode, forknum, and blocknum isn't critical for correctness, but
* helps us get a sequential I/O pattern.
*/
static int
apw_compare_blockinfo(const void *p, const void *q)
{
const BlockInfoRecord *a = (const BlockInfoRecord *) p;
const BlockInfoRecord *b = (const BlockInfoRecord *) q;
cmp_member_elem(database);
cmp_member_elem(tablespace);
cmp_member_elem(filenode);
cmp_member_elem(forknum);
cmp_member_elem(blocknum);
return 0;
}
/*
* Signal handler for SIGTERM
*/
static void
apw_sigterm_handler(SIGNAL_ARGS)
{
int save_errno = errno;
got_sigterm = true;
if (MyProc)
SetLatch(&MyProc->procLatch);
errno = save_errno;
}
/*
* Signal handler for SIGHUP
*/
static void
apw_sighup_handler(SIGNAL_ARGS)
{
int save_errno = errno;
got_sighup = true;
if (MyProc)
SetLatch(&MyProc->procLatch);
errno = save_errno;
}
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