Added --disk-cache option

This option enables disk cache. If SIZE is 0, the disk cache is
disabled. This feature caches the downloaded data in memory, which
grows to at most SIZE bytes. The cache storage is created for aria2
instance and shared by all downloads. The one advantage of the disk
cache is reduce the disk seek time because the data is written in
larger unit and it is reordered by the offset of the file. If the
underlying file is heavily fragmented it is not the case.

1 files changed, 17 insertions, 2 deletions

diff --git a/src/SinkStreamFilter.cc b/src/SinkStreamFilter.cc
index 089cf37e..a5e4566b 100644
--- a/src/SinkStreamFilter.cc
+++ b/src/SinkStreamFilter.cc
@@ -33,14 +33,20 @@
  */
 /* copyright --> */
 #include "SinkStreamFilter.h"
+
+#include <cstring>
+
 #include "BinaryStream.h"
 #include "Segment.h"
+#include "WrDiskCache.h"
+#include "Piece.h"
 
 namespace aria2 {
 
 const std::string SinkStreamFilter::NAME("SinkStreamFilter");
 
-SinkStreamFilter::SinkStreamFilter(bool hashUpdate):
+SinkStreamFilter::SinkStreamFilter(WrDiskCache* wrDiskCache, bool hashUpdate):
+  wrDiskCache_(wrDiskCache),
   hashUpdate_(hashUpdate),
   bytesProcessed_(0) {}
 
@@ -60,7 +66,16 @@ ssize_t SinkStreamFilter::transform
     } else {
       wlen = inlen;
     }
-    out->writeData(inbuf, wlen, segment->getPositionToWrite());
+    const SharedHandle<Piece>& piece = segment->getPiece();
+    if(piece && piece->getWrDiskCacheEntry()) {
+      assert(wrDiskCache_);
+      unsigned char* dataCopy = new unsigned char[wlen];
+      memcpy(dataCopy, inbuf, wlen);
+      piece->updateWrCache(wrDiskCache_, dataCopy, 0, wlen,
+                           segment->getPositionToWrite());
+    } else {
+      out->writeData(inbuf, wlen, segment->getPositionToWrite());
+    }
 #ifdef ENABLE_MESSAGE_DIGEST
     if(hashUpdate_) {
       segment->updateHash(segment->getWrittenLength(), inbuf, wlen);