Add proper per-file copyright notices/licenses and top-level license.

[bluesky.git] / bluesky / cache.c

diff --git a/bluesky/cache.c b/bluesky/cache.c
index 8cd2fb3..838c049 100644 (file)
--- a/bluesky/cache.c
+++ b/bluesky/cache.c
@@ -3,7 +3,29 @@
  * Copyright (C) 2009  The Regents of the University of California
  * Written by Michael Vrable <mvrable@cs.ucsd.edu>
  *
- * TODO: Licensing
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
  */
 
 #define _GNU_SOURCE
@@ -424,18 +446,19 @@ void bluesky_flushd_invoke(BlueSkyFS *fs)
 /* How urgent is flushing out data?  Returns one of several values:
  *   0 - memory state is fine
  *   1 - should launch flushd if not already running
- *   2 - should block writers until memory frees up
+ *   2 - should delay writers while memory frees up
+ *   3 - should block writers until memory frees up
  */
 static int compute_pressure(BlueSkyFS *fs)
 {
-    /* LEVEL 2 */
+    /* LEVEL 3 */
     /* Too much dirty data in memory? */
     if (g_atomic_int_get(&fs->cache_dirty)
                 + g_atomic_int_get(&fs->cache_log_dirty)
            > bluesky_watermark_high_dirty)
     {
-        g_print("pressure: too much dirty data (2)\n");
-        return 2;
+        g_print("pressure: too much dirty data (3)\n");
+        return 3;
     }
 
     /* Too much uncommitted data in the journal on disk, not yet flushed to the
@@ -446,8 +469,20 @@ static int compute_pressure(BlueSkyFS *fs)
     dirty_limit = bluesky_options.cache_size / (LOG_SEGMENT_SIZE / 1024) / 2;
     int dirty_journals = fs->log->seq_num - fs->log->journal_watermark + 1;
     if (dirty_journals > 1 && dirty_journals >= dirty_limit) {
-        printf("pressure: too many dirty journals (%d >= %d) (2)\n",
+        printf("pressure: too many dirty journals (%d >= %d) (3)\n",
                dirty_journals, dirty_limit);
+        return 3;
+    }
+
+    /* LEVEL 2 */
+    if (g_atomic_int_get(&fs->cache_dirty) > bluesky_watermark_med2_dirty) {
+        g_print("pressure: too much dirty data (2)\n");
+        return 2;
+    }
+
+    if (dirty_journals > 1 && dirty_journals > dirty_limit * 3 / 4) {
+        printf("pressure: many dirty journals (%d), should start writeback (2)\n",
+               dirty_journals);
         return 2;
     }
 
@@ -489,10 +524,19 @@ void bluesky_flushd_invoke_conditional(BlueSkyFS *fs)
               g_atomic_int_get(&fs->cache_log_dirty));
         g_mutex_lock(fs->lock);
         pressure = compute_pressure(fs);
-        if (pressure > 1)
+        if (pressure > 2) {
             g_cond_wait(fs->flushd_cond, fs->lock);
+        } else if (pressure > 1) {
+            /* Wait for up to 10 seconds. */
+            GTimeVal timeout;
+            g_get_current_time(&timeout);
+            g_time_val_add(&timeout, 10 * 1000 * 1000);
+            g_cond_timed_wait(fs->flushd_cond, fs->lock, &timeout);
+        }
         g_mutex_unlock(fs->lock);
         pressure = compute_pressure(fs);
+        if (pressure == 1)
+            break;  /* Do not loop indefinitely for a pressure of 1 */
     }
 }