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pg_wait_sampling.c
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/*
* pg_wait_sampling.c
* Track information about wait events.
*
* Copyright (c) 2015-2025, Postgres Professional
*
* IDENTIFICATION
* contrib/pg_wait_sampling/pg_wait_sampling.c
*/
#include "postgres.h"
#include <limits.h>
#include "access/htup_details.h"
#include "catalog/pg_type_d.h"
#include "common/ip.h"
#include "executor/executor.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "optimizer/planner.h"
#include "pg_wait_sampling.h"
#include "pgstat.h"
#include "storage/ipc.h"
#include "storage/latch.h"
#include "storage/lock.h"
#include "storage/lwlock.h"
#include "storage/proc.h"
#include "storage/shm_mq.h"
#include "storage/shm_toc.h"
#include "storage/shmem.h"
#include "tcop/utility.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/timestamp.h"
#include "utils/varlena.h"
#if PG_VERSION_NUM < 150000
#include "postmaster/autovacuum.h"
#include "replication/walsender.h"
#endif
PG_MODULE_MAGIC;
void _PG_init(void);
static bool shmem_initialized = false;
/* Hooks variables */
static ExecutorStart_hook_type prev_ExecutorStart = NULL;
static ExecutorRun_hook_type prev_ExecutorRun = NULL;
static ExecutorFinish_hook_type prev_ExecutorFinish = NULL;
static ExecutorEnd_hook_type prev_ExecutorEnd = NULL;
static planner_hook_type planner_hook_next = NULL;
static ProcessUtility_hook_type prev_ProcessUtility = NULL;
/* Current nesting depth of planner/Executor calls */
static int nesting_level = 0;
/* Pointers to shared memory objects */
shm_mq *pgws_collector_mq = NULL;
uint64 *pgws_proc_queryids = NULL;
CollectorShmqHeader *pgws_collector_hdr = NULL;
/* Receiver (backend) local shm_mq pointers and lock */
static shm_mq *recv_mq = NULL;
static shm_mq_handle *recv_mqh = NULL;
static LOCKTAG queueTag;
/* Hook functions */
#if PG_VERSION_NUM >= 150000
static shmem_request_hook_type prev_shmem_request_hook = NULL;
#endif
static shmem_startup_hook_type prev_shmem_startup_hook = NULL;
static PGPROC *search_proc(int backendPid);
static PlannedStmt *pgws_planner_hook(Query *parse,
#if PG_VERSION_NUM >= 130000
const char *query_string,
#endif
int cursorOptions, ParamListInfo boundParams);
static
#if PG_VERSION_NUM >= 180000
bool
#else
void
#endif
pgws_ExecutorStart(QueryDesc *queryDesc, int eflags);
static void pgws_ExecutorRun(QueryDesc *queryDesc,
ScanDirection direction,
uint64 count
#if PG_VERSION_NUM >= 100000 && PG_VERSION_NUM < 180000
,bool execute_once
#endif
);
static void pgws_ExecutorFinish(QueryDesc *queryDesc);
static void pgws_ExecutorEnd(QueryDesc *queryDesc);
static void pgws_ProcessUtility(PlannedStmt *pstmt,
const char *queryString,
#if PG_VERSION_NUM >= 140000
bool readOnlyTree,
#endif
ProcessUtilityContext context,
ParamListInfo params,
QueryEnvironment *queryEnv,
DestReceiver *dest,
#if PG_VERSION_NUM >= 130000
QueryCompletion *qc
#else
char *completionTag
#endif
);
/*---- GUC variables ----*/
typedef enum
{
PGWS_PROFILE_QUERIES_NONE, /* profile no statements */
PGWS_PROFILE_QUERIES_TOP, /* only top level statements */
PGWS_PROFILE_QUERIES_ALL /* all statements, including nested ones */
} PGWSTrackLevel;
static const struct config_enum_entry pgws_profile_queries_options[] =
{
{"none", PGWS_PROFILE_QUERIES_NONE, false},
{"off", PGWS_PROFILE_QUERIES_NONE, false},
{"no", PGWS_PROFILE_QUERIES_NONE, false},
{"false", PGWS_PROFILE_QUERIES_NONE, false},
{"0", PGWS_PROFILE_QUERIES_NONE, false},
{"top", PGWS_PROFILE_QUERIES_TOP, false},
{"on", PGWS_PROFILE_QUERIES_TOP, false},
{"yes", PGWS_PROFILE_QUERIES_TOP, false},
{"true", PGWS_PROFILE_QUERIES_TOP, false},
{"1", PGWS_PROFILE_QUERIES_TOP, false},
{"all", PGWS_PROFILE_QUERIES_ALL, false},
{NULL, 0, false}
};
int pgws_historySize = 5000;
int pgws_historyPeriod = 10;
int pgws_profilePeriod = 10;
bool pgws_profilePid = true;
int pgws_profileQueries = PGWS_PROFILE_QUERIES_TOP;
bool pgws_sampleCpu = true;
static char *pgws_history_dimensions_string = NULL;
static char *pgws_profile_dimensions_string = NULL;
int pgws_history_dimensions; /* bit mask that is derived from GUC */
int pgws_profile_dimensions; /* bit mask that is derived from GUC */
#define pgws_enabled(level) \
((pgws_profileQueries == PGWS_PROFILE_QUERIES_ALL) || \
(pgws_profileQueries == PGWS_PROFILE_QUERIES_TOP && (level) == 0))
/*
* Calculate max processes count.
*
* The value has to be in sync with ProcGlobal->allProcCount, initialized in
* InitProcGlobal() (proc.c).
*
*/
static int
get_max_procs_count(void)
{
int count = 0;
/* First, add the maximum number of backends (MaxBackends). */
#if PG_VERSION_NUM >= 150000
/*
* On pg15+, we can directly access the MaxBackends variable, as it will
* have already been initialized in shmem_request_hook.
*/
Assert(MaxBackends > 0);
count += MaxBackends;
#else
/*
* On older versions, we need to compute MaxBackends: bgworkers,
* autovacuum workers and launcher. This has to be in sync with the value
* computed in InitializeMaxBackends() (postinit.c)
*
* Note that we need to calculate the value as it won't initialized when
* we need it during _PG_init().
*
* Note also that the value returned during _PG_init() might be different
* from the value returned later if some third-party modules change one of
* the underlying GUC. This isn't ideal but can't lead to a crash, as the
* value returned during _PG_init() is only used to ask for additional
* shmem with RequestAddinShmemSpace(), and postgres has an extra 100kB of
* shmem to compensate some small unaccounted usage. So if the value
* later changes, we will allocate and initialize the new (and correct)
* memory size, which will either work thanks for the extra 100kB of
* shmem, of fail (and prevent postgres startup) due to an out of shared
* memory error.
*/
count += MaxConnections + autovacuum_max_workers + 1
+ max_worker_processes;
/*
* Starting with pg12, wal senders aren't part of MaxConnections anymore
* and have to be accounted for.
*/
count += max_wal_senders;
#endif /* pg 15- */
/* End of MaxBackends calculation. */
/* Add AuxiliaryProcs */
count += NUM_AUXILIARY_PROCS;
return count;
}
/*
* Estimate amount of shared memory needed.
*/
static Size
pgws_shmem_size(void)
{
shm_toc_estimator e;
Size size;
int nkeys;
shm_toc_initialize_estimator(&e);
nkeys = 3;
shm_toc_estimate_chunk(&e, sizeof(CollectorShmqHeader));
shm_toc_estimate_chunk(&e, (Size) COLLECTOR_QUEUE_SIZE);
shm_toc_estimate_chunk(&e, sizeof(uint64) * get_max_procs_count());
shm_toc_estimate_keys(&e, nkeys);
size = shm_toc_estimate(&e);
return size;
}
#if PG_VERSION_NUM >= 150000
/*
* shmem_request hook: request additional shared memory resources.
*
* If you change code here, don't forget to also report the modifications in
* _PG_init() for pg14 and below.
*/
static void
pgws_shmem_request(void)
{
if (prev_shmem_request_hook)
prev_shmem_request_hook();
RequestAddinShmemSpace(pgws_shmem_size());
}
#endif
/*
* Distribute shared memory.
*/
static void
pgws_shmem_startup(void)
{
bool found;
Size segsize = pgws_shmem_size();
void *pgws;
shm_toc *toc;
pgws = ShmemInitStruct("pg_wait_sampling", segsize, &found);
if (!found)
{
/* Create shared objects */
toc = shm_toc_create(PG_WAIT_SAMPLING_MAGIC, pgws, segsize);
pgws_collector_hdr = shm_toc_allocate(toc, sizeof(CollectorShmqHeader));
shm_toc_insert(toc, 0, pgws_collector_hdr);
pgws_collector_mq = shm_toc_allocate(toc, COLLECTOR_QUEUE_SIZE);
shm_toc_insert(toc, 1, pgws_collector_mq);
pgws_proc_queryids = shm_toc_allocate(toc,
sizeof(uint64) * get_max_procs_count());
shm_toc_insert(toc, 2, pgws_proc_queryids);
MemSet(pgws_proc_queryids, 0, sizeof(uint64) * get_max_procs_count());
}
else
{
/* Attach to existing shared objects */
toc = shm_toc_attach(PG_WAIT_SAMPLING_MAGIC, pgws);
pgws_collector_hdr = shm_toc_lookup(toc, 0, false);
pgws_collector_mq = shm_toc_lookup(toc, 1, false);
pgws_proc_queryids = shm_toc_lookup(toc, 2, false);
}
shmem_initialized = true;
if (prev_shmem_startup_hook)
prev_shmem_startup_hook();
}
/*
* Check shared memory is initialized. Report an error otherwise.
*/
static void
check_shmem(void)
{
if (!shmem_initialized)
{
ereport(ERROR, (errcode(ERRCODE_INTERNAL_ERROR),
errmsg("pg_wait_sampling shared memory wasn't initialized yet")));
}
}
static void
pgws_cleanup_callback(int code, Datum arg)
{
elog(DEBUG3, "pg_wait_sampling cleanup: detaching shm_mq and releasing queue lock");
shm_mq_detach(recv_mqh);
LockRelease(&queueTag, ExclusiveLock, false);
}
/*
* Check tokens of string and fill bitmask accordingly
* Mostly copied from plpgsql_extra_checks_check_hook
*/
static bool
pgws_general_dimensions_check_hook (char **newvalue, void **extra, GucSource source)
{
char *rawstring;
List *elemlist;
ListCell *l;
int extrachecks = 0;
int *myextra;
/* Check special cases when we turn all or none dimensions */
if (pg_strcasecmp(*newvalue, "all") == 0)
extrachecks = PGWS_DIMENSIONS_ALL;
else if (pg_strcasecmp(*newvalue, "none") == 0)
extrachecks = PGWS_DIMENSIONS_NONE;
else
{
/* Need a modifiable copy of string */
rawstring = pstrdup(*newvalue);
/* Parse string into list of identifiers */
if (!SplitIdentifierString(rawstring, ',', &elemlist))
{
/* syntax error in list */
GUC_check_errdetail("List syntax is invalid.");
pfree(rawstring);
list_free(elemlist);
return false;
}
/* Loop over all recieved options */
foreach(l, elemlist)
{
char *tok = (char *) lfirst(l);
/* Process all allowed values */
if (pg_strcasecmp(tok, "role_id") == 0)
extrachecks |= PGWS_DIMENSIONS_ROLE_ID;
else if (pg_strcasecmp(tok, "database_id") == 0)
extrachecks |= PGWS_DIMENSIONS_DB_ID;
else if (pg_strcasecmp(tok, "parallel_leader_pid") == 0)
extrachecks |= PGWS_DIMENSIONS_PARALLEL_LEADER_PID;
else if (pg_strcasecmp(tok, "backend_type") == 0)
extrachecks |= PGWS_DIMENSIONS_BE_TYPE;
else if (pg_strcasecmp(tok, "backend_state") == 0)
extrachecks |= PGWS_DIMENSIONS_BE_STATE;
else if (pg_strcasecmp(tok, "backend_start_time") == 0)
extrachecks |= PGWS_DIMENSIONS_BE_START_TIME;
else if (pg_strcasecmp(tok, "client_addr") == 0)
extrachecks |= PGWS_DIMENSIONS_CLIENT_ADDR;
else if (pg_strcasecmp(tok, "client_hostname") == 0)
extrachecks |= PGWS_DIMENSIONS_CLIENT_HOSTNAME;
else if (pg_strcasecmp(tok, "appname") == 0)
extrachecks |= PGWS_DIMENSIONS_APPNAME;
else if (pg_strcasecmp(tok, "all") == 0 || pg_strcasecmp(tok, "none") == 0)
{
GUC_check_errdetail("Key word \"%s\" cannot be combined with other key words.", tok);
pfree(rawstring);
list_free(elemlist);
return false;
}
else
{
GUC_check_errdetail("Unrecognized key word: \"%s\".", tok);
pfree(rawstring);
list_free(elemlist);
return false;
}
}
pfree(rawstring);
list_free(elemlist);
}
#if PG_VERSION_NUM >= 160000
myextra = (int *) guc_malloc(LOG, sizeof(int));
#else
myextra = (int *) malloc(sizeof(int));
#endif
if (!myextra)
return false;
*myextra = extrachecks;
*extra = myextra;
return true;
}
/* Assign actual value to dimension bitmask */
static void
pgws_history_dimensions_assign_hook (const char *newvalue, void *extra)
{
pgws_history_dimensions = *((int *) extra);
}
/* Assign actual value to dimension bitmask */
static void
pgws_profile_dimensions_assign_hook (const char *newvalue, void *extra)
{
pgws_profile_dimensions = *((int *) extra);
}
/*
* Module load callback
*/
void
_PG_init(void)
{
if (!process_shared_preload_libraries_in_progress)
return;
#if PG_VERSION_NUM < 150000
/*
* Request additional shared resources. (These are no-ops if we're not in
* the postmaster process.) We'll allocate or attach to the shared
* resources in pgws_shmem_startup().
*
* If you change code here, don't forget to also report the modifications
* in pgsp_shmem_request() for pg15 and later.
*/
RequestAddinShmemSpace(pgws_shmem_size());
#endif
pgws_register_wait_collector();
/*
* Install hooks.
*/
#if PG_VERSION_NUM >= 150000
prev_shmem_request_hook = shmem_request_hook;
shmem_request_hook = pgws_shmem_request;
#endif
prev_shmem_startup_hook = shmem_startup_hook;
shmem_startup_hook = pgws_shmem_startup;
planner_hook_next = planner_hook;
planner_hook = pgws_planner_hook;
prev_ExecutorStart = ExecutorStart_hook;
ExecutorStart_hook = pgws_ExecutorStart;
prev_ExecutorRun = ExecutorRun_hook;
ExecutorRun_hook = pgws_ExecutorRun;
prev_ExecutorFinish = ExecutorFinish_hook;
ExecutorFinish_hook = pgws_ExecutorFinish;
prev_ExecutorEnd = ExecutorEnd_hook;
ExecutorEnd_hook = pgws_ExecutorEnd;
prev_ProcessUtility = ProcessUtility_hook;
ProcessUtility_hook = pgws_ProcessUtility;
/* Define GUC variables */
DefineCustomIntVariable("pg_wait_sampling.history_size",
"Sets size of waits history.",
NULL,
&pgws_historySize,
5000,
100,
INT_MAX,
PGC_SIGHUP,
0,
NULL,
NULL,
NULL);
DefineCustomIntVariable("pg_wait_sampling.history_period",
"Sets period of waits history sampling.",
NULL,
&pgws_historyPeriod,
10,
1,
INT_MAX,
PGC_SIGHUP,
0,
NULL,
NULL,
NULL);
DefineCustomIntVariable("pg_wait_sampling.profile_period",
"Sets period of waits profile sampling.",
NULL,
&pgws_profilePeriod,
10,
1,
INT_MAX,
PGC_SIGHUP,
0,
NULL,
NULL,
NULL);
DefineCustomBoolVariable("pg_wait_sampling.profile_pid",
"Sets whether profile should be collected per pid.",
NULL,
&pgws_profilePid,
true,
PGC_SIGHUP,
0,
NULL,
NULL,
NULL);
DefineCustomEnumVariable("pg_wait_sampling.profile_queries",
"Sets whether profile should be collected per query.",
NULL,
&pgws_profileQueries,
PGWS_PROFILE_QUERIES_TOP,
pgws_profile_queries_options,
PGC_SIGHUP,
0,
NULL,
NULL,
NULL);
DefineCustomBoolVariable("pg_wait_sampling.sample_cpu",
"Sets whether not waiting backends should be sampled.",
NULL,
&pgws_sampleCpu,
true,
PGC_SIGHUP,
0,
NULL,
NULL,
NULL);
DefineCustomStringVariable("pg_wait_sampling.history_dimensions",
"Sets sampling dimensions for history",
NULL,
&pgws_history_dimensions_string,
"none",
PGC_SIGHUP,
GUC_LIST_INPUT,
pgws_general_dimensions_check_hook,
pgws_history_dimensions_assign_hook,
NULL);
DefineCustomStringVariable("pg_wait_sampling.profile_dimensions",
"Sets sampling dimensions for profile",
NULL,
&pgws_profile_dimensions_string,
"none",
PGC_SIGHUP,
GUC_LIST_INPUT,
pgws_general_dimensions_check_hook,
pgws_profile_dimensions_assign_hook,
NULL);
#if PG_VERSION_NUM >= 150000
MarkGUCPrefixReserved("pg_wait_sampling");
#endif
}
/*
* Find PGPROC entry responsible for given pid assuming ProcArrayLock was
* already taken.
*/
static PGPROC *
search_proc(int pid)
{
int i;
if (pid == 0)
return MyProc;
for (i = 0; i < ProcGlobal->allProcCount; i++)
{
PGPROC *proc = &ProcGlobal->allProcs[i];
if (proc->pid && proc->pid == pid)
{
return proc;
}
}
ereport(ERROR, (errcode(ERRCODE_INTERNAL_ERROR),
errmsg("backend with pid=%d not found", pid)));
return NULL;
}
/*
* Decide whether this PGPROC entry should be included in profiles and output
* views.
*/
bool
pgws_should_sample_proc(PGPROC *proc, int *pid_p, uint32 *wait_event_info_p)
{
int pid = proc->pid;
uint32 wait_event_info = proc->wait_event_info;
*pid_p = pid;
*wait_event_info_p = wait_event_info;
if (wait_event_info == 0 && !pgws_sampleCpu)
return false;
/*
* On PostgreSQL versions < 17 the PGPROC->pid field is not reset on
* process exit. This would lead to such processes getting counted for
* null wait events. So instead we make use of DisownLatch() resetting
* owner_pid during ProcKill().
*/
if (pid == 0 || proc->procLatch.owner_pid == 0 || pid == MyProcPid)
return false;
return true;
}
typedef struct
{
HistoryItem *items;
TimestampTz ts;
} WaitCurrentContext;
PG_FUNCTION_INFO_V1(pg_wait_sampling_get_current);
Datum
pg_wait_sampling_get_current(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
WaitCurrentContext *params;
check_shmem();
if (SRF_IS_FIRSTCALL())
{
MemoryContext oldcontext;
TupleDesc tupdesc;
funcctx = SRF_FIRSTCALL_INIT();
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
params = (WaitCurrentContext *) palloc0(sizeof(WaitCurrentContext));
params->ts = GetCurrentTimestamp();
funcctx->user_fctx = params;
tupdesc = CreateTemplateTupleDesc(4);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "pid",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "type",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "event",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 4, "queryid",
INT8OID, -1, 0);
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
LWLockAcquire(ProcArrayLock, LW_SHARED);
if (!PG_ARGISNULL(0))
{
/* pg_wait_sampling_get_current(pid int4) function */
HistoryItem *item;
PGPROC *proc;
proc = search_proc(PG_GETARG_UINT32(0));
params->items = (HistoryItem *) palloc0(sizeof(HistoryItem));
item = ¶ms->items[0];
item->pid = proc->pid;
item->wait_event_info = proc->wait_event_info;
item->queryId = pgws_proc_queryids[proc - ProcGlobal->allProcs];
funcctx->max_calls = 1;
}
else
{
/* pg_wait_sampling_current view */
int procCount = ProcGlobal->allProcCount,
i,
j = 0;
params->items = (HistoryItem *) palloc0(sizeof(HistoryItem) * procCount);
for (i = 0; i < procCount; i++)
{
PGPROC *proc = &ProcGlobal->allProcs[i];
if (!pgws_should_sample_proc(proc,
¶ms->items[j].pid,
¶ms->items[j].wait_event_info))
continue;
params->items[j].pid = proc->pid;
params->items[j].wait_event_info = proc->wait_event_info;
params->items[j].queryId = pgws_proc_queryids[i];
j++;
}
funcctx->max_calls = j;
}
LWLockRelease(ProcArrayLock);
MemoryContextSwitchTo(oldcontext);
}
/* stuff done on every call of the function */
funcctx = SRF_PERCALL_SETUP();
params = (WaitCurrentContext *) funcctx->user_fctx;
if (funcctx->call_cntr < funcctx->max_calls)
{
HeapTuple tuple;
Datum values[4];
bool nulls[4];
const char *event_type,
*event;
HistoryItem *item;
item = ¶ms->items[funcctx->call_cntr];
/* Make and return next tuple to caller */
MemSet(values, 0, sizeof(values));
MemSet(nulls, 0, sizeof(nulls));
event_type = pgstat_get_wait_event_type(item->wait_event_info);
event = pgstat_get_wait_event(item->wait_event_info);
values[0] = Int32GetDatum(item->pid);
if (event_type)
values[1] = PointerGetDatum(cstring_to_text(event_type));
else
nulls[1] = true;
if (event)
values[2] = PointerGetDatum(cstring_to_text(event));
else
nulls[2] = true;
values[3] = UInt64GetDatum(item->queryId);
tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple));
}
else
{
/* nothing left */
SRF_RETURN_DONE(funcctx);
}
}
static Datum
GetBackendState(BackendState state, bool *is_null)
{
switch (state)
{
#if PG_VERSION_NUM >= 180000
case STATE_STARTING:
return CStringGetTextDatum("starting");
#endif
case STATE_IDLE:
return CStringGetTextDatum("idle");
case STATE_RUNNING:
return CStringGetTextDatum("active");
case STATE_IDLEINTRANSACTION:
return CStringGetTextDatum("idle in transaction");
case STATE_FASTPATH:
return CStringGetTextDatum("fastpath function call");
case STATE_IDLEINTRANSACTION_ABORTED:
return CStringGetTextDatum("idle in transaction (aborted)");
case STATE_DISABLED:
return CStringGetTextDatum("disabled");
case STATE_UNDEFINED:
*is_null = true;
}
return (Datum) 0;
}
/* Copied from pg_stat_get_backend_client_addr */
static Datum
get_backend_client_addr(SockAddr client_addr, bool *is_null)
{
char remote_host[NI_MAXHOST];
int ret;
/* A zeroed client addr means we don't know */
#if PG_VERSION_NUM >= 180000
if (pg_memory_is_all_zeros(&client_addr,
sizeof(client_addr)))
#else
SockAddr zero_clientaddr;
memset(&zero_clientaddr, 0, sizeof(zero_clientaddr));
if (memcmp(&client_addr, &zero_clientaddr,
sizeof(zero_clientaddr)) == 0)
#endif
{
*is_null = true;
return (Datum) 0;
}
switch (client_addr.addr.ss_family)
{
case AF_INET:
case AF_INET6:
break;
default:
*is_null = true;
return (Datum) 0;
}
remote_host[0] = '\0';
ret = pg_getnameinfo_all(&client_addr.addr,
client_addr.salen,
remote_host, sizeof(remote_host),
NULL, 0,
NI_NUMERICHOST | NI_NUMERICSERV);
if (ret != 0)
{
*is_null = true;
return (Datum) 0;
}
clean_ipv6_addr(client_addr.addr.ss_family, remote_host);
return (DirectFunctionCall1(inet_in, CStringGetDatum(remote_host)));
}
/*
* Needed for PostgreSQL 16 and earlier since there is no good way to get
* PgBackendStatus when having only PGPROC structure.
*
* pgstat_fetch_stat_beentry (13-15) works with indices of localBackendStatusTable
* pgstat_get_beentry_by_backend_id (16) works with "backend_ids", but we still
* cannot get them without looking into LocalPgBackendStatus, so work with indices
*
* This function is very inefficient
*
* Maybe we should just iterate over localBackendStatusTable and somehow get
* PGPROC entries from there but it is up for discussion
*/
PgBackendStatus *
get_beentry_by_procpid(int pid)
{
int backend_num = pgstat_fetch_stat_numbackends(), cur_be_idx;
for (cur_be_idx = 1; cur_be_idx <= backend_num; cur_be_idx++)
{
LocalPgBackendStatus *local_beentry;
#if PG_VERSION_NUM >= 160000
local_beentry = pgstat_get_local_beentry_by_index(cur_be_idx);
#else
/* Here beid is just index in localBackendStatusTable */
local_beentry = pgstat_fetch_stat_local_beentry(cur_be_idx);
#endif
if (local_beentry->backendStatus.st_procpid == pid)
return &local_beentry->backendStatus;
}
return NULL;
}
PG_FUNCTION_INFO_V1(pg_wait_sampling_get_current_extended);
Datum
pg_wait_sampling_get_current_extended(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
WaitCurrentContext *params;
check_shmem();
/* Initialization, done only on the first call */
if (SRF_IS_FIRSTCALL())
{
MemoryContext oldcontext;
TupleDesc tupdesc;
funcctx = SRF_FIRSTCALL_INIT();
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
params = (WaitCurrentContext *) palloc0(sizeof(WaitCurrentContext));
params->ts = GetCurrentTimestamp();
funcctx->user_fctx = params;
/* Setup tuple desc */
tupdesc = CreateTemplateTupleDesc(13);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "pid",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "type",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "event",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 4, "queryid",
INT8OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 5, "role_id",
INT8OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 6, "database_id",
INT8OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 7, "parallel_leader_pid",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 8, "backend_type",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 9, "backend_state",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 10, "proc_start",
TIMESTAMPTZOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 11, "client_addr",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 12, "client_hostname",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 13, "appname",
TEXTOID, -1, 0);
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
LWLockAcquire(ProcArrayLock, LW_SHARED);
if (!PG_ARGISNULL(0))
{
/* pg_wait_sampling_get_current_extended(pid int4) function */
HistoryItem *item;
PGPROC *proc;
PgBackendStatus *bestatus;
proc = search_proc(PG_GETARG_UINT32(0));
#if PG_VERSION_NUM >= 170000
bestatus = pgstat_get_beentry_by_proc_number(GetNumberFromPGProc(proc));
#else
bestatus = get_beentry_by_procpid(proc->pid);
#endif
params->items = (HistoryItem *) palloc0(sizeof(HistoryItem));
item = ¶ms->items[0];
/* Show all fields without looking at GUC variables */
item->pid = proc->pid;
item->wait_event_info = proc->wait_event_info;
item->queryId = pgws_proc_queryids[proc - ProcGlobal->allProcs];
item->role_id = proc->roleId;
item->database_id = proc->databaseId;
item->parallel_leader_pid = (proc->lockGroupLeader ?
proc->lockGroupLeader->pid :
0);
if (bestatus)
{
item->backend_type = bestatus->st_backendType;
item->backend_state = bestatus->st_state;
item->proc_start = bestatus->st_proc_start_timestamp;
item->client_addr = bestatus->st_clientaddr;
strcpy(item->client_hostname, bestatus->st_clienthostname);
strcpy(item->appname, bestatus->st_appname);
}
funcctx->max_calls = 1;
}
else
{
/* pg_wait_sampling_current view */
int procCount = ProcGlobal->allProcCount,
i,
j = 0;
params->items = (HistoryItem *) palloc0(sizeof(HistoryItem) * procCount);
for (i = 0; i < procCount; i++)
{
PGPROC *proc = &ProcGlobal->allProcs[i];
#if PG_VERSION_NUM >= 170000
PgBackendStatus *bestatus = pgstat_get_beentry_by_proc_number(GetNumberFromPGProc(proc));
#else
PgBackendStatus *bestatus = get_beentry_by_procpid(proc->pid);
#endif
if (!pgws_should_sample_proc(proc,
¶ms->items[j].pid,
¶ms->items[j].wait_event_info))
continue;
/* Show all fields without looking at GUC variables */
params->items[j].pid = proc->pid;
params->items[j].wait_event_info = proc->wait_event_info;
params->items[j].queryId = pgws_proc_queryids[i];
params->items[j].role_id = proc->roleId;
params->items[j].database_id = proc->databaseId;
params->items[j].parallel_leader_pid = (proc->lockGroupLeader ?
proc->lockGroupLeader->pid :
0);
if (bestatus)
{
params->items[j].backend_type = bestatus->st_backendType;
params->items[j].backend_state = bestatus->st_state;
params->items[j].proc_start = bestatus->st_proc_start_timestamp;
params->items[j].client_addr = bestatus->st_clientaddr;
strcpy(params->items[j].client_hostname, bestatus->st_clienthostname);
strcpy(params->items[j].appname, bestatus->st_appname);
}
j++;
}
funcctx->max_calls = j;
}
LWLockRelease(ProcArrayLock);
#if PG_VERSION_NUM >= 140000
pgstat_clear_backend_activity_snapshot();
#else
pgstat_clear_snapshot();
#endif