From: Jianpeng Ma <jianpeng.ma@intel.com>
Date: Mon, 19 Jan 2015 03:51:40 +0000 (+0800)
Subject: Striper: Add function 'assemble_result(CephContext *cct, char *buffer, size_t len... 
X-Git-Tag: v10.1.0~328^2~1
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=9867804c20583f7ce55fc2daf6c2198f1849905f;p=ceph.git

Striper: Add function 'assemble_result(CephContext *cct, char *buffer, size_t len)' in StripedReadResult.

For sparse read, it can avoid copying zero around.

Signed-off-by: Jianpeng Ma <jianpeng.ma@intel.com>
---

diff --git a/src/librbd/AioCompletion.cc b/src/librbd/AioCompletion.cc
index 765c4cfe5f21..3501032e8089 100644
--- a/src/librbd/AioCompletion.cc
+++ b/src/librbd/AioCompletion.cc
@@ -44,21 +44,25 @@ namespace librbd {
                    << "read_buf=" << reinterpret_cast<void*>(read_buf) << ", "
                    << "real_bl=" <<  reinterpret_cast<void*>(read_bl) << dendl;
     if (rval >= 0 && aio_type == AIO_TYPE_READ) {
-      // FIXME: make the destriper write directly into a buffer so
-      // that we avoid shuffling pointers and copying zeros around.
-      bufferlist bl;
-      destriper.assemble_result(cct, bl, true);
-
-      if (read_buf) {
-	assert(bl.length() == read_buf_len);
-	bl.copy(0, read_buf_len, read_buf);
-	ldout(cct, 20) << "copied resulting " << bl.length()
-		       << " bytes to " << (void*)read_buf << dendl;
-      }
-      if (read_bl) {
-	ldout(cct, 20) << "moving resulting " << bl.length()
-		       << " bytes to bl " << (void*)read_bl << dendl;
-	read_bl->claim(bl);
+      if (read_buf && !read_bl) {
+	destriper.assemble_result(cct, read_buf, read_buf_len);
+      } else {
+	// FIXME: make the destriper write directly into a buffer so
+	// that we avoid shuffling pointers and copying zeros around.
+	bufferlist bl;
+	destriper.assemble_result(cct, bl, true);
+
+	if (read_buf) {
+	  assert(bl.length() == read_buf_len);
+	  bl.copy(0, read_buf_len, read_buf);
+	  ldout(cct, 20) << "copied resulting " << bl.length()
+	    << " bytes to " << (void*)read_buf << dendl;
+	}
+	if (read_bl) {
+	  ldout(cct, 20) << " moving resulting " << bl.length()
+	    << " bytes to bl " << (void*)read_bl << dendl;
+	  read_bl->claim(bl);
+	}
       }
     }
   }
diff --git a/src/osdc/Striper.cc b/src/osdc/Striper.cc
index 43280c82a073..f2bf8fbddcbb 100644
--- a/src/osdc/Striper.cc
+++ b/src/osdc/Striper.cc
@@ -388,3 +388,38 @@ void Striper::StripedReadResult::assemble_result(CephContext *cct,
   partial.clear();
 }
 
+void Striper::StripedReadResult::assemble_result(CephContext *cct, char *buffer, size_t length)
+{
+
+  assert(buffer && length == total_intended_len);
+
+  map<uint64_t,pair<bufferlist,uint64_t> >::reverse_iterator p = partial.rbegin();
+  if (p == partial.rend())
+    return;
+
+  uint64_t curr = length;
+  uint64_t end = p->first + p->second.second;
+  while (p != partial.rend()) {
+    // sanity check
+    ldout(cct, 0) << "assemble_result(" << this << ") " << p->first << "~" << p->second.second
+		   << " " << p->second.first.length() << " bytes"
+		   << dendl;
+    assert(p->first == end - p->second.second);
+    end = p->first;
+
+    size_t len = p->second.first.length();
+    assert(curr >= p->second.second);
+    curr -= p->second.second;
+    if (len < p->second.second) {
+      if (len)
+	p->second.first.copy(0, len, buffer + curr);
+      memset(buffer + curr + len, 0, p->second.second - len);
+    } else {
+      p->second.first.copy(0, len, buffer + curr);
+    }
+    ++p;
+  }
+  partial.clear();
+  assert(curr == 0);
+}
+
diff --git a/src/osdc/Striper.h b/src/osdc/Striper.h
index bbd7eeac25e0..6b5a4e3b67c0 100644
--- a/src/osdc/Striper.h
+++ b/src/osdc/Striper.h
@@ -98,6 +98,12 @@ class CephContext;
 	const vector<pair<uint64_t,uint64_t> >& buffer_extents);
 
       void assemble_result(CephContext *cct, bufferlist& bl, bool zero_tail);
+
+      /**
+       * @buffer copy read data into buffer
+       * @len the length of buffer
+       */
+      void assemble_result(CephContext *cct, char *buffer, size_t len);
     };
 
   };