diff options
Diffstat (limited to 'src/veil_shmem.c')
| -rw-r--r-- | src/veil_shmem.c | 52 |
1 files changed, 47 insertions, 5 deletions
diff --git a/src/veil_shmem.c b/src/veil_shmem.c index ff33c91..14b2bcc 100644 --- a/src/veil_shmem.c +++ b/src/veil_shmem.c @@ -2,7 +2,7 @@ * @file veil_shmem.c * \code * Author: Marc Munro - * Copyright (c) 2005 - 2015 Marc Munro + * Copyright (c) 2005 - 2018 Marc Munro * License: BSD * * \endcode @@ -46,7 +46,7 @@ * - We look up variable "x" in the current hash, and if we have to * allocate space for it, allocate it from the current context. * - * Note that We use a dynamicall allocated LWLock, VeilLWLock to protect + * Note that We use a dynamically allocated LWLock, VeilLWLock to protect * our shared control structures. * */ @@ -100,6 +100,38 @@ static LWLockId InitialLWLock = 0; */ #define OTHER_CONTEXT(x) (x ? 0: 1) +/** + * The MemContext that we use to manage our tranche of LWLocks + */ +static MemContext *lwlock_context; + +/** + * Name of tranche of LWLocks used by veil. + */ +static char *TRANCHE_NAME = "veil"; + +/** + * Return the next LWLock from our tranche. + * Note that locking is the responsibility of the caller. + */ +static LWLock * +NextLWLock() +{ + // TODO: Ensure we don't exceed the number of locks in our tranche + if (lwlock_context->lwlock_idx > 0) { + lwlock_context->lwlock_idx--; + } + else { + // Error + ereport(ERROR, + (errcode(ERRCODE_INTERNAL_ERROR), + errmsg("veil: out of LWLocks"))); + } + return + &(lwlock_context->lwlock_tranche[lwlock_context->lwlock_idx].lock); +} + + /** * Veil's startup function. This should be run when the Veil shared * library is loaded by postgres. @@ -121,8 +153,8 @@ _PG_init() /* Request a Veil-specific shared memory context */ RequestAddinShmemSpace(2 * veil_shmem_context_size() * veil_dbs); - /* Request a LWLock for later use by all backends */ - RequestAddinLWLocks(veil_dbs); + /* Request LWLocks for later use by all backends */ + RequestNamedLWLockTranche(TRANCHE_NAME, veil_dbs); } /** @@ -237,6 +269,15 @@ get_shmem_context(char *name, context->next = sizeof(MemContext); context->limit = size; context->lwlock = VeilLWLock; + + if (i == 0) { + /* This context is the very first MemContext for the + * cluster: this is the one used to manage our LWLocks + * tranche. */ + context->lwlock_tranche = GetNamedLWLockTranche(TRANCHE_NAME); + context->lwlock_idx = max_dbs; + lwlock_context = context; + } return context; } } @@ -399,6 +440,7 @@ vl_free(void *mem) } + /** * Attach to, creating and initialising as necessary, the shared memory * control structure. Record this for the session in shared_meminfo. @@ -449,7 +491,7 @@ shmalloc_init(void) else { /* Allocate new LWLock for this new shared memory * context */ - VeilLWLock = LWLockAssign(); + VeilLWLock = NextLWLock(); } /* Record the lock id in context0 (for possible re-use if * the current database is dropped and a new veil-using |