adb: add implementations of mutex, recursive_mutex.

Our version of mingw doesn't support std::mutex or
std::recursive_mutex, so implement our own using the Windows primitives.

Bug: http://b/28347842
Change-Id: I4e1d56a89bc5fcb5f859bf5014343697a4a85b77

adb/sysdeps/mutex.h

@@ -0,0 +1,107 @@
+#pragma once
+
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#if defined(_WIN32)
+
+#include <windows.h>
+
+#include <android-base/macros.h>
+
+#include "adb.h"
+
+// The prebuilt version of mingw we use doesn't support mutex or recursive_mutex.
+// Therefore, implement our own using the Windows primitives.
+// Put them directly into the std namespace, so that when they're actually available, the build
+// breaks until they're removed.
+
+#include <mutex>
+namespace std {
+
+// CRITICAL_SECTION is recursive, so just wrap it in a Mutex-compatible class.
+class recursive_mutex {
+  public:
+    recursive_mutex() {
+        InitializeCriticalSection(&mutex_);
+    }
+
+    ~recursive_mutex() {
+        DeleteCriticalSection(&mutex_);
+    }
+
+    void lock() {
+        EnterCriticalSection(&mutex_);
+    }
+
+    bool try_lock() {
+        return TryEnterCriticalSection(&mutex_);
+    }
+
+    void unlock() {
+        LeaveCriticalSection(&mutex_);
+    }
+
+  private:
+    CRITICAL_SECTION mutex_;
+
+    DISALLOW_COPY_AND_ASSIGN(recursive_mutex);
+};
+
+class mutex {
+  public:
+    mutex() {
+    }
+
+    ~mutex() {
+    }
+
+    void lock() {
+        mutex_.lock();
+        if (++lock_count_ != 1) {
+            fatal("non-recursive mutex locked reentrantly");
+        }
+    }
+
+    void unlock() {
+        if (--lock_count_ != 0) {
+            fatal("non-recursive mutex unlock resulted in unexpected lock count: %d", lock_count_);
+        }
+        mutex_.unlock();
+    }
+
+    bool try_lock() {
+        if (!mutex_.try_lock()) {
+            return false;
+        }
+
+        if (lock_count_ != 0) {
+            mutex_.unlock();
+            return false;
+        }
+
+        ++lock_count_;
+        return true;
+    }
+
+  private:
+    recursive_mutex mutex_;
+    size_t lock_count_ = 0;
+};
+
+}
+
+#endif

adb/sysdeps_test.cpp

@@ -244,3 +244,60 @@ TEST_F(sysdeps_poll, fd_count) {
         adb_close(fd);
     }
 }
+
+#include "sysdeps/mutex.h"
+TEST(sysdeps_mutex, mutex_smoke) {
+    static std::atomic<bool> finished(false);
+    static std::mutex &m = *new std::mutex();
+    m.lock();
+    ASSERT_FALSE(m.try_lock());
+    adb_thread_create([](void*) {
+        ASSERT_FALSE(m.try_lock());
+        m.lock();
+        finished.store(true);
+        adb_sleep_ms(200);
+        m.unlock();
+    }, nullptr);
+
+    ASSERT_FALSE(finished.load());
+    adb_sleep_ms(100);
+    ASSERT_FALSE(finished.load());
+    m.unlock();
+    adb_sleep_ms(100);
+    m.lock();
+    ASSERT_TRUE(finished.load());
+    m.unlock();
+}
+
+// Our implementation on Windows aborts on double lock.
+#if defined(_WIN32)
+TEST(sysdeps_mutex, mutex_reentrant_lock) {
+    std::mutex &m = *new std::mutex();
+
+    m.lock();
+    ASSERT_FALSE(m.try_lock());
+    EXPECT_DEATH(m.lock(), "non-recursive mutex locked reentrantly");
+}
+#endif
+
+TEST(sysdeps_mutex, recursive_mutex_smoke) {
+    static std::recursive_mutex &m = *new std::recursive_mutex();
+
+    m.lock();
+    ASSERT_TRUE(m.try_lock());
+    m.unlock();
+
+    adb_thread_create([](void*) {
+        ASSERT_FALSE(m.try_lock());
+        m.lock();
+        adb_sleep_ms(500);
+        m.unlock();
+    }, nullptr);
+
+    adb_sleep_ms(100);
+    m.unlock();
+    adb_sleep_ms(100);
+    ASSERT_FALSE(m.try_lock());
+    m.lock();
+    m.unlock();
+}