8000 Add static asserts for MAX_BACKENDS limiting factors · postgrespro/postgres@5ee75e3 · GitHub
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anarazelanarazel
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Add static asserts for MAX_BACKENDS limiting factors
So far the various dependencies were documented in the comment above MAX_BACKENDS, but not checked. Discussion: https://postgr.es/m/CA+COZaBO_s3LfALq=b+HcBHFSOEGiApVjrRacCe4VP9m7CJsNQ@mail.gmail.com
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‎src/backend/storage/lmgr/deadlock.c

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@@ -30,6 +30,7 @@
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#include "pgstat.h"
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#include "storage/lmgr.h"
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#include "storage/proc.h"
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#include "storage/procnumber.h"
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#include "utils/memutils.h"
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@@ -191,6 +192,8 @@ InitDeadLockChecking(void)
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* last MaxBackends entries in possibleConstraints[] are reserved as
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* output workspace for FindLockCycle.
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*/
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StaticAssertStmt(MAX_BACKENDS_BITS <= (32 - 3),
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"MAX_BACKENDS_BITS too big for * 4");
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maxPossibleConstraints = MaxBackends * 4;
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possibleConstraints =
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(EDGE *) palloc(maxPossibleConstraints * sizeof(EDGE));

‎src/backend/utils/cache/inval.c

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@@ -120,6 +120,7 @@
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#include "catalog/catalog.h"
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#include "catalog/pg_constraint.h"
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#include "miscadmin.h"
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#include "storage/procnumber.h"
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#include "storage/sinval.h"
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#include "storage/smgr.h"
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#include "utils/catcache.h"
@@ -1651,6 +1652,10 @@ CacheInvalidateSmgr(RelFileLocatorBackend rlocator)
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{
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SharedInvalidationMessage msg;
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/* verify optimization stated above stays valid */
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StaticAssertStmt(MAX_BACKENDS_BITS <= 23,
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"MAX_BACKEND_BITS is too big for inval.c");
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msg.sm.id = SHAREDINVALSMGR_ID;
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msg.sm.backend_hi = rlocator.backend >> 16;
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msg.sm.backend_lo = rlocator.backend & 0xffff;

‎src/include/storage/buf_internals.h

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@@ -21,6 +21,7 @@
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#include "storage/bufmgr.h"
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#include "storage/condition_variable.h"
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#include "storage/lwlock.h"
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#include "storage/procnumber.h"
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#include "storage/shmem.h"
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#include "storage/smgr.h"
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#include "storage/spin.h"
@@ -86,6 +87,8 @@ StaticAssertDecl(BUF_REFCOUNT_BITS + BUF_USAGECOUNT_BITS + BUF_FLAG_BITS == 32,
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StaticAssertDecl(BM_MAX_USAGE_COUNT < (1 << BUF_USAGECOUNT_BITS),
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"BM_MAX_USAGE_COUNT doesn't fit in BUF_USAGECOUNT_BITS bits");
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StaticAssertDecl(MAX_BACKENDS_BITS <= BUF_REFCOUNT_BITS,
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"MAX_BACKENDS_BITS needs to be <= BUF_REFCOUNT_BITS");
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/*
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* Buffer tag identifies which disk block the buffer contains.

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