From d3c9e9725c8fa014e9ecdd421e967bd53d962b08 Mon Sep 17 00:00:00 2001
From: "Charles E. Rolke" <chug@apache.org>
Date: Fri, 14 Oct 2011 14:57:58 +0000
Subject: QPID-3540 Typecasting and alignment requirements for various
 platforms

In RefCountedBuffer:
1. Pad the instantiantion address of RefCountedBuffer class up to an 8-byte boundary.
2. Add (void *) casts to 'store' pointer to prevent warnings about alignment.

In qpid-perftest:
1. Don't pull a size_t object from an arbitrary buffer address.
Instead, memcopy the object by bytes.


git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk/qpid@1183378 13f79535-47bb-0310-9956-ffa450edef68
---
 cpp/src/qpid/RefCountedBuffer.cpp | 17 ++++++++++++++---
 cpp/src/qpid/RefCountedBuffer.h   | 10 +++++++++-
 cpp/src/tests/qpid-perftest.cpp   |  4 +++-
 3 files changed, 26 insertions(+), 5 deletions(-)

(limited to 'cpp/src')

diff --git a/cpp/src/qpid/RefCountedBuffer.cpp b/cpp/src/qpid/RefCountedBuffer.cpp
index 40d620f7ad..7e15eefeea 100644
--- a/cpp/src/qpid/RefCountedBuffer.cpp
+++ b/cpp/src/qpid/RefCountedBuffer.cpp
@@ -26,15 +26,26 @@ namespace qpid {
 
 void RefCountedBuffer::released() const {
     this->~RefCountedBuffer();
-    ::delete[] reinterpret_cast<const char*>(this);
+    uintptr_t binStoreRaw = reinterpret_cast<uintptr_t>(this);
+    binStoreRaw -= alignPad;
+    ::delete[] reinterpret_cast<const char*>(binStoreRaw);
 }
 
 BufferRef RefCountedBuffer::create(size_t n) {
-    char* store=::new char[n+sizeof(RefCountedBuffer)];
+    char * storeRaw       = ::new char[n + sizeof(RefCountedBuffer) + 
+        refCountedBufferStructAlign];
+    uintptr_t binStoreRaw = reinterpret_cast<uintptr_t>(storeRaw);
+    uintptr_t binStore    = (binStoreRaw +
+        refCountedBufferStructAlign-1) & ~(refCountedBufferStructAlign-1);
+    char * store = reinterpret_cast<char*>(binStore);
+
     new(store) RefCountedBuffer;
+
+    reinterpret_cast<RefCountedBuffer*>((void *)store)->alignPad = binStore - binStoreRaw;
+
     char* start = store+sizeof(RefCountedBuffer);
     return BufferRef(
-        boost::intrusive_ptr<RefCounted>(reinterpret_cast<RefCountedBuffer*>(store)),
+        boost::intrusive_ptr<RefCounted>(reinterpret_cast<RefCountedBuffer*>((void *)store)),
         start, start+n);
 }
 
diff --git a/cpp/src/qpid/RefCountedBuffer.h b/cpp/src/qpid/RefCountedBuffer.h
index f0ea86130b..67a512d938 100644
--- a/cpp/src/qpid/RefCountedBuffer.h
+++ b/cpp/src/qpid/RefCountedBuffer.h
@@ -28,8 +28,14 @@
 namespace qpid {
 
 /**
- * Reference-counted byte buffer. No alignment guarantees.
+ * Reference-counted byte buffer. Alignment guarantees:
+ * The RefCountedBuffer structure is aligned to the 
+ *   refCountedBUfferStructAlign byte boundary specified here.
+ * The buffer itself has no alignment guarantees.
  */
+
+static const size_t refCountedBufferStructAlign = 8;
+
 class RefCountedBuffer : public RefCounted {
   public:
     /** Create a reference counted buffer of size n */
@@ -37,6 +43,8 @@ class RefCountedBuffer : public RefCounted {
 
   protected:
     void released() const;
+
+    size_t alignPad;
 };
 
 } // namespace qpid
diff --git a/cpp/src/tests/qpid-perftest.cpp b/cpp/src/tests/qpid-perftest.cpp
index 3aff742c62..dd81354adb 100644
--- a/cpp/src/tests/qpid-perftest.cpp
+++ b/cpp/src/tests/qpid-perftest.cpp
@@ -644,7 +644,9 @@ struct SubscribeThread : public Client {
                     //
                     // For now verify order only for a single publisher.
                     size_t offset = opts.uniqueData ? 5 /*marker is 'data:'*/ : 0;
-                    size_t n = *reinterpret_cast<const size_t*>(msg.getData().data() + offset);
+                    size_t n;
+                    memcpy (&n, reinterpret_cast<const char*>(msg.getData().data() + offset),
+                        sizeof(n));
                     if (opts.pubs == 1) {
                         if (opts.subs == 1 || opts.mode == FANOUT) verify(n==expect, "==", expect, n);
                         else verify(n>=expect, ">=", expect, n);
-- 
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