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Replace spinlock with LWLock

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This commit is contained in:
Kosntantin Knizhnik
2025-07-17 21:55:28 +03:00
committed by Konstantin Knizhnik
parent 67c31b61e8
commit 1c0f4d6f97
2 changed files with 28 additions and 16 deletions
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5
pgxn/neon/pagestore_smgr.c
View File

@@ -1615,6 +1615,11 @@ neon_write(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum, const vo
{
/* We do not know relation persistence: let's determine it */
relkind = mdexists(reln, debug_compare_local ? INIT_FORKNUM : forknum) ? RELKIND_UNLOGGED : RELKIND_PERMANENT;
/*
* There is no lock hold between get_cached_relkind and set_cached_relkind.
* We assume that multiple backends can repeat this check and get the same result (there is assert in set_cached_relkind).
* And concurrent setting UNLOGGED_BUILD is not possible because only one relation can perform unlogged build.
*/
set_cached_relkind(rinfo, relkind);
}
if (relkind == RELKIND_UNLOGGED_BUILD)

39
pgxn/neon/relkind_cache.c
View File

@@ -49,7 +49,6 @@ typedef struct
uint64 hits;
uint64 misses;
uint64 pinned;
slock_t mutex;
dlist_head lru; /* double linked list for LRU replacement
* algorithm */
} RelKindHashControl;
@@ -64,6 +63,7 @@ static void relkind_shmem_request(void);
#endif
LWLockId finish_unlogged_build_lock;
LWLockId relkind_hash_lock;
/*
* Size of a cache entry is 32 bytes. So this default will take about 2 MB,
@@ -94,14 +94,14 @@ relkind_cache_startup(void)
* relation and hence hold one more entry in the cache pinned.
*/
size_t hash_size = Max(2 * MaxBackends, relkind_hash_size);
finish_unlogged_build_lock = (LWLockId) GetNamedLWLockTranche("neon_relkind");
relkind_hash_lock = (LWLockId) GetNamedLWLockTranche("neon_relkind");
finish_unlogged_build_lock = (LWLockId)(GetNamedLWLockTranche("neon_relkind") + 1);
info.keysize = sizeof(NRelFileInfo);
info.entrysize = sizeof(RelKindEntry);
relkind_hash = ShmemInitHash("neon_relkind",
hash_size, hash_size,
&info,
HASH_ELEM | HASH_BLOBS);
SpinLockInit(&relkind_ctl->mutex);
relkind_ctl->size = 0;
relkind_ctl->hits = 0;
relkind_ctl->misses = 0;
@@ -181,11 +181,12 @@ pin_cached_relkind(NRelFileInfo rinfo, RelKind relkind)
{
RelKindEntry *entry;
/* Use spinlock to prevent concurrent hash modifitcation */
SpinLockAcquire(&relkind_ctl->mutex);
LWLockAcquire(relkind_hash_lock, LW_EXCLUSIVE);
entry = get_pinned_entry(rinfo);
entry->relkind = relkind;
SpinLockRelease(&relkind_ctl->mutex);
LWLockRelease(relkind_hash_lock);
return entry;
}
@@ -202,7 +203,8 @@ get_cached_relkind(NRelFileInfo rinfo)
RelKindEntry *entry;
RelKind relkind = RELKIND_UNKNOWN;
SpinLockAcquire(&relkind_ctl->mutex);
LWLockAcquire(relkind_hash_lock, LW_EXCLUSIVE);
entry = hash_search(relkind_hash, &rinfo, HASH_FIND, NULL);
if (entry != NULL)
{
@@ -215,7 +217,7 @@ get_cached_relkind(NRelFileInfo rinfo)
relkind = entry->relkind;
unpin_entry(entry);
}
SpinLockRelease(&relkind_ctl->mutex);
LWLockRelease(relkind_hash_lock);
return relkind;
}
@@ -228,13 +230,15 @@ set_cached_relkind(NRelFileInfo rinfo, RelKind relkind)
{
RelKindEntry *entry;
SpinLockAcquire(&relkind_ctl->mutex);
LWLockAcquire(relkind_hash_lock, LW_EXCLUSIVE);
/* Do pin+unpin entry to move it to the end of LRU list */
entry = get_pinned_entry(rinfo);
Assert(entry->relkind == RELKIND_UNKNOWN || entry->relkind == relkind);
entry->relkind = relkind;
unpin_entry(entry);
SpinLockRelease(&relkind_ctl->mutex);
LWLockRelease(relkind_hash_lock);
}
void
@@ -242,9 +246,9 @@ unpin_cached_relkind(RelKindEntry* entry)
{
if (entry)
{
SpinLockAcquire(&relkind_ctl->mutex);
LWLockAcquire(relkind_hash_lock, LW_EXCLUSIVE);
unpin_entry(entry);
SpinLockRelease(&relkind_ctl->mutex);
LWLockRelease(relkind_hash_lock);
}
}
@@ -252,7 +256,9 @@ void
forget_cached_relkind(NRelFileInfo rinfo)
{
RelKindEntry *entry;
SpinLockAcquire(&relkind_ctl->mutex);
LWLockAcquire(relkind_hash_lock, LW_EXCLUSIVE);
entry = hash_search(relkind_hash, &rinfo, HASH_REMOVE, NULL);
if (entry)
{
@@ -260,7 +266,8 @@ forget_cached_relkind(NRelFileInfo rinfo)
dlist_delete(&entry->lru_node);
relkind_ctl->size -= 1;
}
SpinLockRelease(&relkind_ctl->mutex);
LWLockRelease(relkind_hash_lock);
}
@@ -285,7 +292,7 @@ relkind_hash_init(void)
shmem_request_hook = relkind_shmem_request;
#else
RequestAddinShmemSpace(hash_estimate_size(relkind_hash_size, sizeof(RelKindEntry)));
RequestNamedLWLockTranche("neon_relkind", 1);
RequestNamedLWLockTranche("neon_relkind", 2);
#endif
prev_shmem_startup_hook = shmem_startup_hook;
@@ -304,6 +311,6 @@ relkind_shmem_request(void)
prev_shmem_request_hook();
RequestAddinShmemSpace(sizeof(RelKindHashControl) + hash_estimate_size(relkind_hash_size, sizeof(RelKindEntry)));
RequestNamedLWLockTranche("neon_relkind", 1);
RequestNamedLWLockTranche("neon_relkind", 2);
}
#endif