Use a different thread for every different type of background job

src/aof.c

@@ -771,7 +771,7 @@ void backgroundRewriteDoneHandler(int exitcode, int bysignal) {
         redisLog(REDIS_NOTICE, "Background AOF rewrite successful");
 
         /* Asynchronously close the overwritten AOF. */
-        if (oldfd != -1) bioCreateBackgroundJob(REDIS_BIO_CLOSE_FILE,(void*)(long)oldfd);
+        if (oldfd != -1) bioCreateBackgroundJob(REDIS_BIO_CLOSE_FILE,(void*)(long)oldfd,NULL,NULL);
 
         redisLog(REDIS_VERBOSE,
             "Background AOF rewrite signal handler took %lldus", ustime()-now);

src/bio.c

@@ -16,7 +16,10 @@
  * ------
  *
  * The design is trivial, we have a structure representing a job to perform
- * and a single thread performing all the I/O operations in the queue.
+ * and a different thread and job queue for every job type.
+ * Every thread wait for new jobs in its queue, and process every job
+ * sequentially.
+ *
  * Currently there is no way for the creator of the job to be notified about
  * the completion of the operation, this will only be added when/if needed.
  */
@@ -24,22 +27,24 @@
 #include "redis.h"
 #include "bio.h"
 
-static pthread_mutex_t bio_mutex;
-static pthread_cond_t bio_condvar;
-static list *bio_jobs;
+static pthread_mutex_t bio_mutex[REDIS_BIO_NUM_OPS];
+static pthread_cond_t bio_condvar[REDIS_BIO_NUM_OPS];
+static list *bio_jobs[REDIS_BIO_NUM_OPS];
 /* The following array is used to hold the number of pending jobs for every
  * OP type. This allows us to export the bioPendingJobsOfType() API that is
  * useful when the main thread wants to perform some operation that may involve
  * objects shared with the background thread. The main thread will just wait
  * that there are no longer jobs of this type to be executed before performing
  * the sensible operation. This data is also useful for reporting. */
-static unsigned long long *bio_pending;
+static unsigned long long bio_pending[REDIS_BIO_NUM_OPS];
 
 /* This structure represents a background Job. It is only used locally to this
  * file as the API deos not expose the internals at all. */
 struct bio_job {
-    int type;       /* Job type, for instance BIO_JOB_CLOSE */
-    void *data;     /* Job specific arguments pointer. */
+    time_t time; /* Time at which the job was created. */
+    /* Job specific arguments pointers. If we need to pass more than three
+     * arguments we can just pass a pointer to a structure or alike. */
+    void *arg1, *arg2, *arg3;
 };
 
 void *bioProcessBackgroundJobs(void *arg);
@@ -56,11 +61,12 @@ void bioInit(void) {
     int j;
 
     /* Initialization of state vars and objects */
-    pthread_mutex_init(&bio_mutex,NULL);
-    pthread_cond_init(&bio_condvar,NULL);
-    bio_jobs = listCreate();
-    bio_pending = zmalloc(sizeof(*bio_pending)*REDIS_BIO_MAX_OP_ID);
-    for (j = 0; j < REDIS_BIO_MAX_OP_ID; j++) bio_pending[j] = 0;
+    for (j = 0; j < REDIS_BIO_NUM_OPS; j++) {
+        pthread_mutex_init(&bio_mutex[j],NULL);
+        pthread_cond_init(&bio_condvar[j],NULL);
+        bio_jobs[j] = listCreate();
+        bio_pending[j] = 0;
+    }
 
     /* Set the stack size as by default it may be small in some system */
     pthread_attr_init(&attr);
@@ -69,52 +75,57 @@ void bioInit(void) {
     while (stacksize < REDIS_THREAD_STACK_SIZE) stacksize *= 2;
     pthread_attr_setstacksize(&attr, stacksize);
 
-    /* Ready to spawn our thread */
-    if (pthread_create(&thread,&attr,bioProcessBackgroundJobs,NULL) != 0) {
-        redisLog(REDIS_WARNING,"Fatal: Can't initialize Background Jobs.");
-        exit(1);
+    /* Ready to spawn our threads. We use the single argument the thread
+     * function accepts in order to pass the job ID the thread is
+     * responsible of. */
+    for (j = 0; j < REDIS_BIO_NUM_OPS; j++) {
+        void *arg = (void*)(unsigned long) j;
+        if (pthread_create(&thread,&attr,bioProcessBackgroundJobs,arg) != 0) {
+            redisLog(REDIS_WARNING,"Fatal: Can't initialize Background Jobs.");
+            exit(1);
+        }
     }
 }
 
-void bioCreateBackgroundJob(int type, void *data) {
+void bioCreateBackgroundJob(int type, void *arg1, void *arg2, void *arg3) {
     struct bio_job *job = zmalloc(sizeof(*job));
 
-    job->type = type;
-    job->data = data;
-    pthread_mutex_lock(&bio_mutex);
-    listAddNodeTail(bio_jobs,job);
+    job->time = time(NULL);
+    job->arg1 = arg1;
+    job->arg2 = arg2;
+    job->arg3 = arg3;
+    pthread_mutex_lock(&bio_mutex[type]);
+    listAddNodeTail(bio_jobs[type],job);
     bio_pending[type]++;
-    pthread_cond_signal(&bio_condvar);
-    pthread_mutex_unlock(&bio_mutex);
+    pthread_cond_signal(&bio_condvar[type]);
+    pthread_mutex_unlock(&bio_mutex[type]);
 }
 
 void *bioProcessBackgroundJobs(void *arg) {
     struct bio_job *job;
-    REDIS_NOTUSED(arg);
+    unsigned long type = (unsigned long) arg;
 
     pthread_detach(pthread_self());
-    pthread_mutex_lock(&bio_mutex);
+    pthread_mutex_lock(&bio_mutex[type]);
     while(1) {
         listNode *ln;
-        int type;
 
         /* The loop always starts with the lock hold. */
-        if (listLength(bio_jobs) == 0) {
-            pthread_cond_wait(&bio_condvar,&bio_mutex);
+        if (listLength(bio_jobs[type]) == 0) {
+            pthread_cond_wait(&bio_condvar[type],&bio_mutex[type]);
             continue;
         }
         /* Pop the job from the queue. */
-        ln = listFirst(bio_jobs);
+        ln = listFirst(bio_jobs[type]);
         job = ln->value;
-        type = job->type;
-        listDelNode(bio_jobs,ln);
+        listDelNode(bio_jobs[type],ln);
         /* It is now possible to unlock the background system as we know have
          * a stand alone job structure to process.*/
-        pthread_mutex_unlock(&bio_mutex);
+        pthread_mutex_unlock(&bio_mutex[type]);
 
         /* Process the job accordingly to its type. */
         if (type == REDIS_BIO_CLOSE_FILE) {
-            close((long)job->data);
+            close((long)job->arg1);
         } else {
             redisPanic("Wrong job type in bioProcessBackgroundJobs().");
         }
@@ -122,7 +133,7 @@ void *bioProcessBackgroundJobs(void *arg) {
 
         /* Lock again before reiterating the loop, if there are no longer
          * jobs to process we'll block again in pthread_cond_wait(). */
-        pthread_mutex_lock(&bio_mutex);
+        pthread_mutex_lock(&bio_mutex[type]);
         bio_pending[type]--;
     }
 }
@@ -130,9 +141,9 @@ void *bioProcessBackgroundJobs(void *arg) {
 /* Return the number of pending jobs of the specified type. */
 unsigned long long bioPendingJobsOfType(int type) {
     unsigned long long val;
-    pthread_mutex_lock(&bio_mutex);
+    pthread_mutex_lock(&bio_mutex[type]);
     val = bio_pending[type];
-    pthread_mutex_unlock(&bio_mutex);
+    pthread_mutex_unlock(&bio_mutex[type]);
     return val;
 }
 
@@ -164,3 +175,18 @@ void bioWaitPendingJobsLE(int type, unsigned long long num) {
         if (bioPendingJobsOfType(type) <= num) break;
     }
 }
+
+/* Return the older job of the specified type. */
+time_t bioOlderJobOfType(int type) {
+    time_t time;
+    listNode *ln;
+    struct bio_job *job;
+
+    pthread_mutex_lock(&bio_mutex[type]);
+    ln = listFirst(bio_jobs[type]);
+    job = ln->value;
+    time = job->time;
+    pthread_mutex_unlock(&bio_mutex[type]);
+    return time;
+}
+

src/bio.h

 /* Exported API */
 void bioInit(void);
-void bioCreateBackgroundJob(int type, void *data);
+void bioCreateBackgroundJob(int type, void *arg1, void *arg2, void *arg3);
 unsigned long long bioPendingJobsOfType(int type);
 void bioWaitPendingJobsLE(int type, unsigned long long num);
+time_t bioOlderJobOfType(int type);
 
 /* Background job opcodes */
-#define REDIS_BIO_ZERO_OP_ID    0 /* We don't use zero as it is the most likely
-                                   * passed value in case of bugs/races. */
-#define REDIS_BIO_CLOSE_FILE    1 /* Deferred close(2) syscall. */
-#define REDIS_BIO_MAX_OP_ID     1
+#define REDIS_BIO_CLOSE_FILE    0 /* Deferred close(2) syscall. */
+#define REDIS_BIO_NUM_OPS       1