From: Michael Vrable <mvrable@cs.ucsd.edu>
Date: Fri, 12 Nov 2010 03:12:47 +0000 (-0800)
Subject: Add a prefetch method.  At the moment it is a no-op.
X-Git-Url: http://git.vrable.net/?p=bluesky.git;a=commitdiff_plain;h=7f47ef48ce38ab71fc414bee592a9078ed1c0a7a

Add a prefetch method.  At the moment it is a no-op.
---

diff --git a/bluesky/bluesky-private.h b/bluesky/bluesky-private.h
index 7735a91..dcd7c48 100644
--- a/bluesky/bluesky-private.h
+++ b/bluesky/bluesky-private.h
@@ -332,6 +332,7 @@ void bluesky_cloudlog_sync(BlueSkyCloudLog *log);
 void bluesky_cloudlog_insert(BlueSkyCloudLog *log);
 void bluesky_cloudlog_insert_locked(BlueSkyCloudLog *log);
 BlueSkyCloudLog *bluesky_cloudlog_get(BlueSkyFS *fs, BlueSkyCloudID id);
+void bluesky_cloudlog_prefetch(BlueSkyCloudLog *log);
 void bluesky_cloudlog_fetch(BlueSkyCloudLog *log);
 BlueSkyCloudPointer bluesky_cloudlog_serialize(BlueSkyCloudLog *log,
                                                BlueSkyFS *fs);
diff --git a/bluesky/cloudlog.c b/bluesky/cloudlog.c
index a37776a..7730d0e 100644
--- a/bluesky/cloudlog.c
+++ b/bluesky/cloudlog.c
@@ -268,6 +268,16 @@ BlueSkyCloudLog *bluesky_cloudlog_get(BlueSkyFS *fs, BlueSkyCloudID id)
     return item;
 }
 
+/* Attempt to prefetch a cloud log item.  This does not guarantee that it will
+ * be made available, but does make it more likely that a future call to
+ * bluesky_cloudlog_fetch will complete quickly. */
+void bluesky_cloudlog_prefetch(BlueSkyCloudLog *log)
+{
+    gchar *id = bluesky_cloudlog_id_to_string(log->id);
+    g_print("Prefetch for %s\n", id);
+    g_free(id);
+}
+
 /* Ensure that a cloud log item is loaded in memory, and if not read it in.
  * TODO: Make asynchronous, and make this also fetch from the cloud.  Right now
  * we only read from the log.  Log item must be locked. */
diff --git a/bluesky/file.c b/bluesky/file.c
index 7b11e70..a4a8108 100644
--- a/bluesky/file.c
+++ b/bluesky/file.c
@@ -192,6 +192,16 @@ void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
     }
 #endif
 
+    uint64_t start_block, end_block;
+    start_block = offset / BLUESKY_BLOCK_SIZE;
+    end_block = (offset + len - 1) / BLUESKY_BLOCK_SIZE;
+    for (uint64_t i = start_block; i <= end_block; i++) {
+        BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
+                                         i);
+        if (b->type == BLUESKY_BLOCK_REF)
+            bluesky_cloudlog_prefetch(b->ref);
+    }
+
     while (len > 0) {
         uint64_t block_num = offset / BLUESKY_BLOCK_SIZE;
         gint block_offset = offset % BLUESKY_BLOCK_SIZE;