From: Kern Sibbald <kern@sibbald.com>
Date: Wed, 19 Mar 2003 10:16:08 +0000 (+0000)
Subject: Minor cleanup of semaphore scheduling code
X-Git-Tag: Release-1.30~82
X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=2ea7021fd31d1bf7273f4a727f20e91a9c2637d9;p=bacula%2Fbacula

Minor cleanup of semaphore scheduling code


git-svn-id: https://bacula.svn.sourceforge.net/svnroot/bacula/trunk@385 91ce42f0-d328-0410-95d8-f526ca767f89
---

diff --git a/bacula/kernstodo b/bacula/kernstodo
index eb15b2f1ea..b143903f8f 100644
--- a/bacula/kernstodo
+++ b/bacula/kernstodo
@@ -21,6 +21,8 @@ Testing to do: (painful)
 - ***test GetFileAttributexEx, and remove MessageBox at 335 of winservice.cpp ****
 
 For 1.30 release:
+- If tape is marked read-only, then try opening it read-only rather than
+  failing, and remember that it cannot be written.
 - Refine SD waiting output:
     Device is being positioned
     >     Device is being positioned for append
diff --git a/bacula/src/dird/job.c b/bacula/src/dird/job.c
index b35be631d1..c12788da50 100644
--- a/bacula/src/dird/job.c
+++ b/bacula/src/dird/job.c
@@ -54,6 +54,7 @@ extern void backup_cleanup(void);
 static semlock_t job_lock;
 static pthread_mutex_t mutex;
 static pthread_cond_t  resource_wait;
+static int waiting = 0; 	      /* count of waiting threads */
 #else
 /* Queue of jobs to be run */
 workq_t job_wq; 		  /* our job work queue */
@@ -248,6 +249,11 @@ static void *job_thread(void *arg)
    return NULL;
 }
 
+/*
+ * Acquire the resources needed. These locks limit the
+ *  number of jobs by each resource. We have limits on
+ *  Jobs, Clients, Storage, and total jobs.
+ */
 static int acquire_resource_locks(JCR *jcr)
 {
 #ifdef USE_SEMAPHORE
@@ -306,8 +312,13 @@ static int acquire_resource_locks(JCR *jcr)
 
 wait:
       P(mutex);
-      /* Wait for some resource to be released */
+      /*
+       * Wait for a resource to be released either by backoff or
+       *  by a job terminating.
+       */
+      waiting++;
       pthread_cond_wait(&resource_wait, &mutex);
+      waiting--;
       V(mutex);
       /* Try again */
    }
@@ -316,20 +327,43 @@ wait:
 }
 
 #ifdef USE_SEMAPHORE
+/*
+ * We could not get all the resource locks because 
+ *  too many jobs are running, so release any locks
+ *  we did acquire, giving others a chance to use them
+ *  while we wait.
+ */
 static void backoff_resource_locks(JCR *jcr, int count)
 {
+   P(mutex);
    switch (count) {
    case 3:
       sem_unlock(&jcr->store->sem);
+      /* Fall through wanted */
    case 2:
       sem_unlock(&jcr->client->sem);
+      /* Fall through wanted */
    case 1:
       sem_unlock(&jcr->job->sem);
       break;
    }
+   /*
+    * Since we released a lock, if there are any threads
+    *  waiting, wake them up so that they can try again.
+    */
+   if (waiting > 0) {
+      pthread_cond_broadcast(&resource_wait);
+   }
+   V(mutex);
 }
 #endif
 
+/*
+ * This is called at the end of the job to release
+ *   any resource limits on the number of jobs. If
+ *   there are any other jobs waiting, we wake them
+ *   up so that they can try again.
+ */
 static void release_resource_locks(JCR *jcr)
 {
 #ifdef USE_SEMAPHORE
@@ -338,7 +372,9 @@ static void release_resource_locks(JCR *jcr)
    sem_unlock(&jcr->client->sem);
    sem_unlock(&jcr->job->sem);
    sem_unlock(&job_lock);
-   pthread_cond_signal(&resource_wait);
+   if (waiting > 0) {
+      pthread_cond_broadcast(&resource_wait);
+   }
    V(mutex);
 #endif
 }
diff --git a/bacula/src/version.h b/bacula/src/version.h
index 909e06a87c..d6c3321a44 100644
--- a/bacula/src/version.h
+++ b/bacula/src/version.h
@@ -1,8 +1,8 @@
 /* */
 #define VERSION "1.30"
 #define VSTRING "1"
-#define BDATE   "17 March 2003"
-#define LSMDATE "17Mar03"
+#define BDATE   "19 March 2003"
+#define LSMDATE "19Mar03"
 
 /* Debug flags */
 #define DEBUG 1