83 lines
2.2 KiB
C
83 lines
2.2 KiB
C
#define REDISMODULE_EXPERIMENTAL_API
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#include "redismodule.h"
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#include <assert.h>
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#include <stdio.h>
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#include <pthread.h>
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#define UNUSED(V) ((void) V)
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void *sub_worker(void *arg) {
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// Get Redis module context
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RedisModuleCtx *ctx = (RedisModuleCtx *)arg;
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// Try acquiring GIL
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int res = RedisModule_ThreadSafeContextTryLock(ctx);
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// GIL is already taken by the calling thread expecting to fail.
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assert(res != REDISMODULE_OK);
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return NULL;
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}
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void *worker(void *arg) {
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// Retrieve blocked client
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RedisModuleBlockedClient *bc = (RedisModuleBlockedClient *)arg;
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// Get Redis module context
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RedisModuleCtx *ctx = RedisModule_GetThreadSafeContext(bc);
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// Acquire GIL
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RedisModule_ThreadSafeContextLock(ctx);
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// Create another thread which will try to acquire the GIL
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pthread_t tid;
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int res = pthread_create(&tid, NULL, sub_worker, ctx);
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assert(res == 0);
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// Wait for thread
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pthread_join(tid, NULL);
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// Release GIL
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RedisModule_ThreadSafeContextUnlock(ctx);
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// Reply to client
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RedisModule_ReplyWithSimpleString(ctx, "OK");
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// Unblock client
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RedisModule_UnblockClient(bc, NULL);
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return NULL;
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}
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int acquire_gil(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
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{
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UNUSED(argv);
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UNUSED(argc);
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/* This command handler tries to acquire the GIL twice
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* once in the worker thread using "RedisModule_ThreadSafeContextLock"
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* second in the sub-worker thread
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* using "RedisModule_ThreadSafeContextTryLock"
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* as the GIL is already locked. */
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RedisModuleBlockedClient *bc = RedisModule_BlockClient(ctx, NULL, NULL, NULL, 0);
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pthread_t tid;
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int res = pthread_create(&tid, NULL, worker, bc);
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assert(res == 0);
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return REDISMODULE_OK;
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}
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int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
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REDISMODULE_NOT_USED(argv);
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REDISMODULE_NOT_USED(argc);
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if (RedisModule_Init(ctx, "blockedclient", 1, REDISMODULE_APIVER_1)== REDISMODULE_ERR)
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return REDISMODULE_ERR;
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if (RedisModule_CreateCommand(ctx, "acquire_gil", acquire_gil, "", 0, 0, 0) == REDISMODULE_ERR)
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return REDISMODULE_ERR;
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return REDISMODULE_OK;
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}
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