Line data Source code
1 : /* -------------------------------------------------------------------------
2 : *
3 : * pgstat_replslot.c
4 : * Implementation of replication slot statistics.
5 : *
6 : * This file contains the implementation of replication slot statistics. It is kept
7 : * separate from pgstat.c to enforce the line between the statistics access /
8 : * storage implementation and the details about individual types of
9 : * statistics.
10 : *
11 : * Replication slot stats work a bit different than other variable-numbered
12 : * stats. Slots do not have oids (so they can be created on physical
13 : * replicas). Use the slot index as object id while running. However, the slot
14 : * index can change when restarting. That is addressed by using the name when
15 : * (de-)serializing. After a restart it is possible for slots to have been
16 : * dropped while shut down, which is addressed by not restoring stats for
17 : * slots that cannot be found by name when starting up.
18 : *
19 : * Copyright (c) 2001-2026, PostgreSQL Global Development Group
20 : *
21 : * IDENTIFICATION
22 : * src/backend/utils/activity/pgstat_replslot.c
23 : * -------------------------------------------------------------------------
24 : */
25 :
26 : #include "postgres.h"
27 :
28 : #include "replication/slot.h"
29 : #include "utils/pgstat_internal.h"
30 :
31 :
32 : static int get_replslot_index(const char *name, bool need_lock);
33 :
34 :
35 : /*
36 : * Reset counters for a single replication slot.
37 : *
38 : * Permission checking for this function is managed through the normal
39 : * GRANT system.
40 : */
41 : void
42 4 : pgstat_reset_replslot(const char *name)
43 : {
44 : ReplicationSlot *slot;
45 :
46 : Assert(name != NULL);
47 :
48 4 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
49 :
50 : /* Check if the slot exists with the given name. */
51 4 : slot = SearchNamedReplicationSlot(name, false);
52 4 : if (!slot)
53 1 : ereport(ERROR,
54 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
55 : errmsg("replication slot \"%s\" does not exist",
56 : name)));
57 :
58 : /*
59 : * Reset stats if it is a logical slot. Nothing to do for physical slots
60 : * as we collect stats only for logical slots.
61 : */
62 3 : if (SlotIsLogical(slot))
63 3 : pgstat_reset(PGSTAT_KIND_REPLSLOT, InvalidOid,
64 3 : ReplicationSlotIndex(slot));
65 :
66 3 : LWLockRelease(ReplicationSlotControlLock);
67 3 : }
68 :
69 : /*
70 : * Report replication slot statistics.
71 : *
72 : * We can rely on the stats for the slot to exist and to belong to this
73 : * slot. We can only get here if pgstat_create_replslot() or
74 : * pgstat_acquire_replslot() have already been called.
75 : */
76 : void
77 6169 : pgstat_report_replslot(ReplicationSlot *slot, const PgStat_StatReplSlotEntry *repSlotStat)
78 : {
79 : PgStat_EntryRef *entry_ref;
80 : PgStatShared_ReplSlot *shstatent;
81 : PgStat_StatReplSlotEntry *statent;
82 :
83 6169 : entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_REPLSLOT, InvalidOid,
84 6169 : ReplicationSlotIndex(slot), false);
85 6169 : shstatent = (PgStatShared_ReplSlot *) entry_ref->shared_stats;
86 6169 : statent = &shstatent->stats;
87 :
88 : /* Update the replication slot statistics */
89 : #define REPLSLOT_ACC(fld) statent->fld += repSlotStat->fld
90 6169 : REPLSLOT_ACC(spill_txns);
91 6169 : REPLSLOT_ACC(spill_count);
92 6169 : REPLSLOT_ACC(spill_bytes);
93 6169 : REPLSLOT_ACC(stream_txns);
94 6169 : REPLSLOT_ACC(stream_count);
95 6169 : REPLSLOT_ACC(stream_bytes);
96 6169 : REPLSLOT_ACC(mem_exceeded_count);
97 6169 : REPLSLOT_ACC(total_txns);
98 6169 : REPLSLOT_ACC(total_bytes);
99 : #undef REPLSLOT_ACC
100 :
101 6169 : pgstat_unlock_entry(entry_ref);
102 6169 : }
103 :
104 : /*
105 : * Report replication slot sync skip statistics.
106 : *
107 : * Similar to pgstat_report_replslot(), we can rely on the stats for the
108 : * slot to exist and to belong to this slot.
109 : */
110 : void
111 2 : pgstat_report_replslotsync(ReplicationSlot *slot)
112 : {
113 : PgStat_EntryRef *entry_ref;
114 : PgStatShared_ReplSlot *shstatent;
115 : PgStat_StatReplSlotEntry *statent;
116 :
117 : /* Slot sync stats are valid only for synced logical slots on standby. */
118 : Assert(slot->data.synced);
119 : Assert(RecoveryInProgress());
120 :
121 2 : entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_REPLSLOT, InvalidOid,
122 2 : ReplicationSlotIndex(slot), false);
123 : Assert(entry_ref != NULL);
124 :
125 2 : shstatent = (PgStatShared_ReplSlot *) entry_ref->shared_stats;
126 2 : statent = &shstatent->stats;
127 :
128 2 : statent->slotsync_skip_count += 1;
129 2 : statent->slotsync_last_skip = GetCurrentTimestamp();
130 :
131 2 : pgstat_unlock_entry(entry_ref);
132 2 : }
133 :
134 : /*
135 : * Report replication slot creation.
136 : *
137 : * NB: This gets called with ReplicationSlotAllocationLock already held, be
138 : * careful about calling back into slot.c.
139 : */
140 : void
141 488 : pgstat_create_replslot(ReplicationSlot *slot)
142 : {
143 : PgStat_EntryRef *entry_ref;
144 : PgStatShared_ReplSlot *shstatent;
145 :
146 : Assert(LWLockHeldByMeInMode(ReplicationSlotAllocationLock, LW_EXCLUSIVE));
147 :
148 488 : entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_REPLSLOT, InvalidOid,
149 488 : ReplicationSlotIndex(slot), false);
150 488 : shstatent = (PgStatShared_ReplSlot *) entry_ref->shared_stats;
151 :
152 : /*
153 : * NB: need to accept that there might be stats from an older slot, e.g.
154 : * if we previously crashed after dropping a slot.
155 : */
156 488 : memset(&shstatent->stats, 0, sizeof(shstatent->stats));
157 :
158 488 : pgstat_unlock_entry(entry_ref);
159 488 : }
160 :
161 : /*
162 : * Report replication slot has been acquired.
163 : *
164 : * This guarantees that a stats entry exists during later
165 : * pgstat_report_replslot() or pgstat_report_replslotsync() calls.
166 : *
167 : * If we previously crashed, no stats data exists. But if we did not crash,
168 : * the stats do belong to this slot:
169 : * - the stats cannot belong to a dropped slot, pgstat_drop_replslot() would
170 : * have been called
171 : * - if the slot was removed while shut down,
172 : * pgstat_replslot_from_serialized_name_cb() returning false would have
173 : * caused the stats to be dropped
174 : */
175 : void
176 1111 : pgstat_acquire_replslot(ReplicationSlot *slot)
177 : {
178 1111 : pgstat_get_entry_ref(PGSTAT_KIND_REPLSLOT, InvalidOid,
179 1111 : ReplicationSlotIndex(slot), true, NULL);
180 1111 : }
181 :
182 : /*
183 : * Report replication slot drop.
184 : */
185 : void
186 423 : pgstat_drop_replslot(ReplicationSlot *slot)
187 : {
188 : Assert(LWLockHeldByMeInMode(ReplicationSlotAllocationLock, LW_EXCLUSIVE));
189 :
190 423 : if (!pgstat_drop_entry(PGSTAT_KIND_REPLSLOT, InvalidOid,
191 423 : ReplicationSlotIndex(slot)))
192 48 : pgstat_request_entry_refs_gc();
193 423 : }
194 :
195 : /*
196 : * Support function for the SQL-callable pgstat* functions. Returns
197 : * a pointer to the replication slot statistics struct.
198 : */
199 : PgStat_StatReplSlotEntry *
200 52 : pgstat_fetch_replslot(NameData slotname)
201 : {
202 : int idx;
203 52 : PgStat_StatReplSlotEntry *slotentry = NULL;
204 :
205 52 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
206 :
207 52 : idx = get_replslot_index(NameStr(slotname), false);
208 :
209 52 : if (idx != -1)
210 50 : slotentry = (PgStat_StatReplSlotEntry *) pgstat_fetch_entry(PGSTAT_KIND_REPLSLOT,
211 : InvalidOid, idx);
212 :
213 52 : LWLockRelease(ReplicationSlotControlLock);
214 :
215 52 : return slotentry;
216 : }
217 :
218 : void
219 106 : pgstat_replslot_to_serialized_name_cb(const PgStat_HashKey *key, const PgStatShared_Common *header, NameData *name)
220 : {
221 : /*
222 : * This is only called late during shutdown. The set of existing slots
223 : * isn't allowed to change at this point, we can assume that a slot exists
224 : * at the offset.
225 : */
226 106 : if (!ReplicationSlotName(key->objid, name))
227 0 : elog(ERROR, "could not find name for replication slot index %" PRIu64,
228 : key->objid);
229 106 : }
230 :
231 : bool
232 76 : pgstat_replslot_from_serialized_name_cb(const NameData *name, PgStat_HashKey *key)
233 : {
234 76 : int idx = get_replslot_index(NameStr(*name), true);
235 :
236 : /* slot might have been deleted */
237 76 : if (idx == -1)
238 1 : return false;
239 :
240 75 : key->kind = PGSTAT_KIND_REPLSLOT;
241 75 : key->dboid = InvalidOid;
242 75 : key->objid = idx;
243 :
244 75 : return true;
245 : }
246 :
247 : void
248 8 : pgstat_replslot_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
249 : {
250 8 : ((PgStatShared_ReplSlot *) header)->stats.stat_reset_timestamp = ts;
251 8 : }
252 :
253 : static int
254 128 : get_replslot_index(const char *name, bool need_lock)
255 : {
256 : ReplicationSlot *slot;
257 :
258 : Assert(name != NULL);
259 :
260 128 : slot = SearchNamedReplicationSlot(name, need_lock);
261 :
262 128 : if (!slot)
263 3 : return -1;
264 :
265 125 : return ReplicationSlotIndex(slot);
266 : }
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