From 7e44b2dd4d5326dbb4acdbe27a19c3c0a28829ea Mon Sep 17 00:00:00 2001
From: mutouyun <mark.lonr@tom.com>
Date: Wed, 16 Jan 2019 13:56:25 +0800
Subject: [PATCH] shm would fail with multi-thread accessing

---
 src/platform/shm_linux.cpp | 34 +++++++++++++++++++++-------------
 test/test_shm.cpp          | 10 ++++++++++
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/src/platform/shm_linux.cpp b/src/platform/shm_linux.cpp
index 056c200..9ab4763 100644
--- a/src/platform/shm_linux.cpp
+++ b/src/platform/shm_linux.cpp
@@ -8,8 +8,9 @@
 
 #include <atomic>
 #include <string>
+#include <utility>
+#include <mutex>
 
-#include "tls_pointer.h"
 #include "memory/resource.hpp"
 
 namespace {
@@ -24,9 +25,12 @@ constexpr void* mem_of(void* mem) {
     return static_cast<acc_t*>(mem) - 1;
 }
 
-inline auto& m2h() {
-    static ipc::tls::pointer<ipc::mem::unordered_map<void*, std::string>> cache;
-    return *cache.create();
+inline auto* m2h() {
+    static struct {
+        std::mutex lc_;
+        ipc::mem::unordered_map<void*, std::string> cache_;
+    } m2h_;
+    return &m2h_;
 }
 
 } // internal-linkage
@@ -38,29 +42,32 @@ void* acquire(char const * name, std::size_t size) {
     if (name == nullptr || name[0] == '\0' || size == 0) {
         return nullptr;
     }
-    int fd = ::shm_open((std::string{"__IPC_SHM__"} + name).c_str(),
-                        O_CREAT | O_RDWR,
-                        S_IRUSR | S_IWUSR |
-                        S_IRGRP | S_IWGRP |
-                        S_IROTH | S_IWOTH);
+    std::string op_name = std::string{"__IPC_SHM__"} + name;
+    int fd = ::shm_open(op_name.c_str(), O_CREAT | O_RDWR,
+                                         S_IRUSR | S_IWUSR |
+                                         S_IRGRP | S_IWGRP |
+                                         S_IROTH | S_IWOTH);
     if (fd == -1) {
         return nullptr;
     }
     size += sizeof(acc_t);
     if (::ftruncate(fd, static_cast<off_t>(size)) != 0) {
         ::close(fd);
-        ::shm_unlink(name);
+        ::shm_unlink(op_name.c_str());
         return nullptr;
     }
     void* mem = ::mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
     ::close(fd);
     if (mem == MAP_FAILED) {
-        ::shm_unlink(name);
+        ::shm_unlink(op_name.c_str());
         return nullptr;
     }
     auto acc = acc_of(mem);
     acc->fetch_add(1, std::memory_order_release);
-    m2h().emplace(++acc, name);
+    {
+        [[maybe_unused]] auto guard = std::unique_lock { m2h()->lc_ };
+        m2h()->cache_.emplace(++acc, std::move(op_name));
+    }
     return acc;
 }
 
@@ -68,7 +75,8 @@ void release(void* mem, std::size_t size) {
     if (mem == nullptr) {
         return;
     }
-    auto& cc = m2h();
+    [[maybe_unused]] auto guard = std::unique_lock { m2h()->lc_ };
+    auto& cc = m2h()->cache_;
     auto it = cc.find(mem);
     if (it == cc.end()) {
         return;
diff --git a/test/test_shm.cpp b/test/test_shm.cpp
index de6d8a3..0535f37 100644
--- a/test/test_shm.cpp
+++ b/test/test_shm.cpp
@@ -17,6 +17,8 @@ class Unit : public TestSuite {
     }
 
 private slots:
+    void cleanupTestCase();
+
     void test_acquire();
     void test_release();
     void test_get();
@@ -28,6 +30,10 @@ private slots:
 
 handle shm_hd__;
 
+void Unit::cleanupTestCase() {
+    shm_hd__.release();
+}
+
 void Unit::test_acquire() {
     QVERIFY(!shm_hd__.valid());
 
@@ -97,6 +103,10 @@ void Unit::test_mt() {
     }.join();
     QVERIFY(shm_hd__.get() == nullptr);
     QVERIFY(!shm_hd__.valid());
+
+    QVERIFY(shm_hd__.acquire("my-test", 1024));
+    std::uint8_t buf[1024] = {};
+    QVERIFY(memcmp(shm_hd__.get(), buf, sizeof(buf)) == 0);
 }
 
 } // internal-linkage