From 3c714fd9e0ae153ca0fadde8fdbc551aca61a623 Mon Sep 17 00:00:00 2001
From: Alexey Rybalchenko <alexryba@gmail.com>
Date: Wed, 18 Oct 2023 13:01:28 +0200
Subject: [PATCH] Message::SetUsedSize: add optional alignment argument, to
 avoid storing alignment with the msg object

---
 fairmq/Message.h        |  2 +-
 fairmq/shmem/Message.h  | 10 +++++++---
 fairmq/zeromq/Message.h |  2 +-
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/fairmq/Message.h b/fairmq/Message.h
index 9b57318a..f065085e 100644
--- a/fairmq/Message.h
+++ b/fairmq/Message.h
@@ -46,7 +46,7 @@ struct Message
     virtual void* GetData() const = 0;
     virtual size_t GetSize() const = 0;
 
-    virtual bool SetUsedSize(size_t size) = 0;
+    virtual bool SetUsedSize(size_t size, Alignment alignment = Alignment{0}) = 0;
 
     virtual Transport GetType() const = 0;
     TransportFactory* GetTransport() { return fTransport; }
diff --git a/fairmq/shmem/Message.h b/fairmq/shmem/Message.h
index 502034e9..eedd8700 100644
--- a/fairmq/shmem/Message.h
+++ b/fairmq/shmem/Message.h
@@ -257,7 +257,7 @@ class Message final : public fair::mq::Message
 
     size_t GetSize() const override { return fSize; }
 
-    bool SetUsedSize(size_t newSize) override
+    bool SetUsedSize(size_t newSize, Alignment alignment = Alignment{0}) override
     {
         if (newSize == fSize) {
             return true;
@@ -266,8 +266,8 @@ class Message final : public fair::mq::Message
             return true;
         } else if (newSize <= fSize) {
             try {
+                char* oldPtr = fManager.GetAddressFromHandle(fHandle, fSegmentId);
                 try {
-                    char* oldPtr = fManager.GetAddressFromHandle(fHandle, fSegmentId);
                     uint16_t userOffset = ShmHeader::UserOffset(oldPtr);
                     char* ptr = fManager.ShrinkInPlace(userOffset + newSize, oldPtr, fSegmentId);
                     fLocalPtr = ShmHeader::UserPtr(ptr);
@@ -278,7 +278,11 @@ class Message final : public fair::mq::Message
                     // unused size >= 1000000 bytes: reallocate fully
                     // unused size < 1000000 bytes: simply reset the size and keep the rest of the buffer until message destruction
                     if (fSize - newSize >= 1000000) {
-                        char* ptr = fManager.Allocate(newSize, fAlignment);
+                        if (alignment.alignment == 0) {
+                            // if no alignment is provided, take the minimum alignment of the old pointer, but no more than 4096
+                            alignment.alignment = 1 << std::min(__builtin_ctz(reinterpret_cast<size_t>(oldPtr)), 12);
+                        }
+                        char* ptr = fManager.Allocate(newSize, alignment.alignment);
                         char* userPtr = ShmHeader::UserPtr(ptr);
                         std::memcpy(userPtr, fLocalPtr, newSize);
                         fManager.Deallocate(fHandle, fSegmentId);
diff --git a/fairmq/zeromq/Message.h b/fairmq/zeromq/Message.h
index 9624229c..a00bfb0c 100644
--- a/fairmq/zeromq/Message.h
+++ b/fairmq/zeromq/Message.h
@@ -210,7 +210,7 @@ class Message final : public fair::mq::Message
     // destroyed. Used size is applied only once in ApplyUsedSize, which is called by the socket
     // before sending. This function just updates the desired size until the actual "resizing"
     // happens.
-    bool SetUsedSize(size_t size) override
+    bool SetUsedSize(size_t size, Alignment /* alignment */ = Alignment{0}) override
     {
         if (size == GetSize()) {
             // nothing to do