From: Michael Vrable <mvrable@cs.ucsd.edu>
Date: Fri, 5 Mar 2010 22:25:29 +0000 (-0800)
Subject: Start fetch of all blocks in a read at the start of the read operation.
X-Git-Url: https://git.vrable.net/?a=commitdiff_plain;h=7d9e06cc3154631da14e573648940c4d6176ae9a;p=bluesky.git

Start fetch of all blocks in a read at the start of the read operation.
---

diff --git a/bluesky/file.c b/bluesky/file.c
index 822c2c8..66f84e7 100644
--- a/bluesky/file.c
+++ b/bluesky/file.c
@@ -157,6 +157,25 @@ void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
     g_return_if_fail(offset < inode->size);
     g_return_if_fail(len <= inode->size - offset);
 
+    /* Start fetches on any data blocks that we will need for this read. */
+    BlueSkyStoreAsync *barrier = bluesky_store_async_new(inode->fs->store);
+    barrier->op = STORE_OP_BARRIER;
+    uint64_t start_block, end_block;
+    start_block = offset / BLUESKY_BLOCK_SIZE;
+    end_block = (offset + len - 1) / BLUESKY_BLOCK_SIZE;
+    g_print("Start prefetch on blocks %"PRIi64" .. %"PRIi64"\n",
+            start_block, end_block);
+    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_block_fetch(inode->fs, b, barrier);
+    }
+    bluesky_store_async_submit(barrier);
+    bluesky_store_async_wait(barrier);
+    bluesky_store_async_unref(barrier);
+    g_print("Prefetch complete.\n");
+
     while (len > 0) {
         uint64_t block_num = offset / BLUESKY_BLOCK_SIZE;
         gint block_offset = offset % BLUESKY_BLOCK_SIZE;