diff --git a/liblog/fake_log_device.cpp b/liblog/fake_log_device.cpp
index 4143fa6..1fb88e3 100644
--- a/liblog/fake_log_device.cpp
+++ b/liblog/fake_log_device.cpp
@@ -48,21 +48,20 @@
 #define TRACE(...) ((void)0)
 #endif
 
-static int FakeAvailable(log_id_t);
-static int FakeOpen();
 static void FakeClose();
 static int FakeWrite(log_id_t log_id, struct timespec* ts, struct iovec* vec, size_t nr);
 
 struct android_log_transport_write fakeLoggerWrite = {
     .name = "fake",
     .logMask = 0,
-    .available = FakeAvailable,
-    .open = FakeOpen,
+    .available = [](log_id_t) { return 0; },
+    .open = [] { return 0; },
     .close = FakeClose,
     .write = FakeWrite,
 };
 
 typedef struct LogState {
+  bool initialized = false;
   /* global minimum priority */
   int global_min_priority;
 
@@ -76,19 +75,8 @@
   } tagSet[kTagSetSize];
 } LogState;
 
-/*
- * Locking.  Since we're emulating a device, we need to be prepared
- * to have multiple callers at the same time.  This lock is used
- * to both protect the fd list and to prevent LogStates from being
- * freed out from under a user.
- */
-std::mutex mutex;
-
 static LogState log_state;
-
-static int FakeAvailable(log_id_t) {
-  return 0;
-}
+static std::mutex fake_log_mutex;
 
 /*
  * Configure logging based on ANDROID_LOG_TAGS environment variable.  We
@@ -103,8 +91,8 @@
  * We also want to check ANDROID_PRINTF_LOG to determine how the output
  * will look.
  */
-int FakeOpen() {
-  std::lock_guard guard{mutex};
+void InitializeLogStateLocked() {
+  log_state.initialized = true;
 
   /* global min priority defaults to "info" level */
   log_state.global_min_priority = ANDROID_LOG_INFO;
@@ -129,7 +117,7 @@
       }
       if (i == kMaxTagLen) {
         TRACE("ERROR: env tag too long (%d chars max)\n", kMaxTagLen - 1);
-        return 0;
+        return;
       }
       tagName[i] = '\0';
 
@@ -180,7 +168,7 @@
         if (*tags != '\0' && !isspace(*tags)) {
           TRACE("ERROR: garbage in tag env; expected whitespace\n");
           TRACE("       env='%s'\n", tags);
-          return 0;
+          return;
         }
       }
 
@@ -224,7 +212,6 @@
   }
 
   log_state.output_format = format;
-  return 0;
 }
 
 /*
@@ -474,7 +461,11 @@
    * Also guarantees that only one thread is in showLog() at a given
    * time (if it matters).
    */
-  std::lock_guard guard{mutex};
+  auto lock = std::lock_guard{fake_log_mutex};
+
+  if (!log_state.initialized) {
+    InitializeLogStateLocked();
+  }
 
   if (log_id == LOG_ID_EVENTS || log_id == LOG_ID_STATS || log_id == LOG_ID_SECURITY) {
     TRACE("%s: ignoring binary log\n", android_log_id_to_name(log_id));
@@ -532,7 +523,7 @@
  * help debug HOST tools ...
  */
 static void FakeClose() {
-  std::lock_guard guard{mutex};
+  auto lock = std::lock_guard{fake_log_mutex};
 
   memset(&log_state, 0, sizeof(log_state));
 }
diff --git a/liblog/logd_writer.cpp b/liblog/logd_writer.cpp
index a22c3be..283a979 100644
--- a/liblog/logd_writer.cpp
+++ b/liblog/logd_writer.cpp
@@ -30,97 +30,80 @@
 #include <time.h>
 #include <unistd.h>
 
+#include <shared_mutex>
+
 #include <cutils/sockets.h>
 #include <private/android_filesystem_config.h>
 #include <private/android_logger.h>
 
 #include "log_portability.h"
 #include "logger.h"
+#include "rwlock.h"
 #include "uio.h"
 
-static int logdAvailable(log_id_t LogId);
-static int logdOpen();
-static void logdClose();
-static int logdWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr);
+static int LogdWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr);
+static void LogdClose();
 
 struct android_log_transport_write logdLoggerWrite = {
     .name = "logd",
     .logMask = 0,
-    .context.sock = -EBADF,
-    .available = logdAvailable,
-    .open = logdOpen,
-    .close = logdClose,
-    .write = logdWrite,
+    .available = [](log_id_t) { return 0; },
+    .open = [] { return 0; },
+    .close = LogdClose,
+    .write = LogdWrite,
 };
 
-/* log_init_lock assumed */
-static int logdOpen() {
-  int i, ret = 0;
+static int logd_socket;
+static RwLock logd_socket_lock;
 
-  i = atomic_load(&logdLoggerWrite.context.sock);
-  if (i < 0) {
-    int sock = TEMP_FAILURE_RETRY(socket(PF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0));
-    if (sock < 0) {
-      ret = -errno;
-    } else {
-      struct sockaddr_un un;
-      memset(&un, 0, sizeof(struct sockaddr_un));
-      un.sun_family = AF_UNIX;
-      strcpy(un.sun_path, "/dev/socket/logdw");
-
-      if (TEMP_FAILURE_RETRY(connect(sock, (struct sockaddr*)&un, sizeof(struct sockaddr_un))) <
-          0) {
-        ret = -errno;
-        switch (ret) {
-          case -ENOTCONN:
-          case -ECONNREFUSED:
-          case -ENOENT:
-            i = atomic_exchange(&logdLoggerWrite.context.sock, ret);
-            [[fallthrough]];
-          default:
-            break;
-        }
-        close(sock);
-      } else {
-        ret = atomic_exchange(&logdLoggerWrite.context.sock, sock);
-        if ((ret >= 0) && (ret != sock)) {
-          close(ret);
-        }
-        ret = 0;
-      }
-    }
+static void OpenSocketLocked() {
+  logd_socket = TEMP_FAILURE_RETRY(socket(PF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0));
+  if (logd_socket <= 0) {
+    return;
   }
 
-  return ret;
-}
+  sockaddr_un un = {};
+  un.sun_family = AF_UNIX;
+  strcpy(un.sun_path, "/dev/socket/logdw");
 
-static void __logdClose(int negative_errno) {
-  int sock = atomic_exchange(&logdLoggerWrite.context.sock, negative_errno);
-  if (sock >= 0) {
-    close(sock);
+  if (TEMP_FAILURE_RETRY(
+          connect(logd_socket, reinterpret_cast<sockaddr*>(&un), sizeof(sockaddr_un))) < 0) {
+    close(logd_socket);
+    logd_socket = 0;
   }
 }
 
-static void logdClose() {
-  __logdClose(-EBADF);
+static void OpenSocket() {
+  auto lock = std::unique_lock{logd_socket_lock};
+  if (logd_socket > 0) {
+    // Someone raced us and opened the socket already.
+    return;
+  }
+
+  OpenSocketLocked();
 }
 
-static int logdAvailable(log_id_t logId) {
-  if (logId >= LOG_ID_MAX || logId == LOG_ID_KERNEL) {
-    return -EINVAL;
+static void ResetSocket(int old_socket) {
+  auto lock = std::unique_lock{logd_socket_lock};
+  if (old_socket != logd_socket) {
+    // Someone raced us and reset the socket already.
+    return;
   }
-  if (atomic_load(&logdLoggerWrite.context.sock) < 0) {
-    if (access("/dev/socket/logdw", W_OK) == 0) {
-      return 0;
-    }
-    return -EBADF;
-  }
-  return 1;
+  close(logd_socket);
+  logd_socket = 0;
+  OpenSocketLocked();
 }
 
-static int logdWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr) {
+static void LogdClose() {
+  auto lock = std::unique_lock{logd_socket_lock};
+  if (logd_socket > 0) {
+    close(logd_socket);
+  }
+  logd_socket = 0;
+}
+
+static int LogdWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr) {
   ssize_t ret;
-  int sock;
   static const unsigned headerLength = 1;
   struct iovec newVec[nr + headerLength];
   android_log_header_t header;
@@ -128,15 +111,16 @@
   static atomic_int dropped;
   static atomic_int droppedSecurity;
 
-  sock = atomic_load(&logdLoggerWrite.context.sock);
-  if (sock < 0) switch (sock) {
-      case -ENOTCONN:
-      case -ECONNREFUSED:
-      case -ENOENT:
-        break;
-      default:
-        return -EBADF;
-    }
+  auto lock = std::shared_lock{logd_socket_lock};
+  if (logd_socket <= 0) {
+    lock.unlock();
+    OpenSocket();
+    lock.lock();
+  }
+
+  if (logd_socket <= 0) {
+    return -EBADF;
+  }
 
   /* logd, after initialization and priv drop */
   if (__android_log_uid() == AID_LOGD) {
@@ -155,41 +139,39 @@
   newVec[0].iov_base = (unsigned char*)&header;
   newVec[0].iov_len = sizeof(header);
 
-  if (sock >= 0) {
-    int32_t snapshot = atomic_exchange_explicit(&droppedSecurity, 0, memory_order_relaxed);
-    if (snapshot) {
-      android_log_event_int_t buffer;
+  int32_t snapshot = atomic_exchange_explicit(&droppedSecurity, 0, memory_order_relaxed);
+  if (snapshot) {
+    android_log_event_int_t buffer;
 
-      header.id = LOG_ID_SECURITY;
-      buffer.header.tag = LIBLOG_LOG_TAG;
-      buffer.payload.type = EVENT_TYPE_INT;
-      buffer.payload.data = snapshot;
+    header.id = LOG_ID_SECURITY;
+    buffer.header.tag = LIBLOG_LOG_TAG;
+    buffer.payload.type = EVENT_TYPE_INT;
+    buffer.payload.data = snapshot;
 
-      newVec[headerLength].iov_base = &buffer;
-      newVec[headerLength].iov_len = sizeof(buffer);
+    newVec[headerLength].iov_base = &buffer;
+    newVec[headerLength].iov_len = sizeof(buffer);
 
-      ret = TEMP_FAILURE_RETRY(writev(sock, newVec, 2));
-      if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) {
-        atomic_fetch_add_explicit(&droppedSecurity, snapshot, memory_order_relaxed);
-      }
+    ret = TEMP_FAILURE_RETRY(writev(logd_socket, newVec, 2));
+    if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) {
+      atomic_fetch_add_explicit(&droppedSecurity, snapshot, memory_order_relaxed);
     }
-    snapshot = atomic_exchange_explicit(&dropped, 0, memory_order_relaxed);
-    if (snapshot && __android_log_is_loggable_len(ANDROID_LOG_INFO, "liblog", strlen("liblog"),
-                                                  ANDROID_LOG_VERBOSE)) {
-      android_log_event_int_t buffer;
+  }
+  snapshot = atomic_exchange_explicit(&dropped, 0, memory_order_relaxed);
+  if (snapshot && __android_log_is_loggable_len(ANDROID_LOG_INFO, "liblog", strlen("liblog"),
+                                                ANDROID_LOG_VERBOSE)) {
+    android_log_event_int_t buffer;
 
-      header.id = LOG_ID_EVENTS;
-      buffer.header.tag = LIBLOG_LOG_TAG;
-      buffer.payload.type = EVENT_TYPE_INT;
-      buffer.payload.data = snapshot;
+    header.id = LOG_ID_EVENTS;
+    buffer.header.tag = LIBLOG_LOG_TAG;
+    buffer.payload.type = EVENT_TYPE_INT;
+    buffer.payload.data = snapshot;
 
-      newVec[headerLength].iov_base = &buffer;
-      newVec[headerLength].iov_len = sizeof(buffer);
+    newVec[headerLength].iov_base = &buffer;
+    newVec[headerLength].iov_len = sizeof(buffer);
 
-      ret = TEMP_FAILURE_RETRY(writev(sock, newVec, 2));
-      if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) {
-        atomic_fetch_add_explicit(&dropped, snapshot, memory_order_relaxed);
-      }
+    ret = TEMP_FAILURE_RETRY(writev(logd_socket, newVec, 2));
+    if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) {
+      atomic_fetch_add_explicit(&dropped, snapshot, memory_order_relaxed);
     }
   }
 
@@ -208,49 +190,26 @@
     }
   }
 
-  /*
-   * The write below could be lost, but will never block.
-   *
-   * ENOTCONN occurs if logd has died.
-   * ENOENT occurs if logd is not running and socket is missing.
-   * ECONNREFUSED occurs if we can not reconnect to logd.
-   * EAGAIN occurs if logd is overloaded.
-   */
-  if (sock < 0) {
-    ret = sock;
-  } else {
-    ret = TEMP_FAILURE_RETRY(writev(sock, newVec, i));
-    if (ret < 0) {
-      ret = -errno;
-    }
+  // The write below could be lost, but will never block.
+  // EAGAIN occurs if logd is overloaded, other errors indicate that something went wrong with
+  // the connection, so we reset it and try again.
+  ret = TEMP_FAILURE_RETRY(writev(logd_socket, newVec, i));
+  if (ret < 0 && errno != EAGAIN) {
+    int old_socket = logd_socket;
+    lock.unlock();
+    ResetSocket(old_socket);
+    lock.lock();
+
+    ret = TEMP_FAILURE_RETRY(writev(logd_socket, newVec, i));
   }
-  switch (ret) {
-    case -ENOTCONN:
-    case -ECONNREFUSED:
-    case -ENOENT:
-      if (__android_log_trylock()) {
-        return ret; /* in a signal handler? try again when less stressed */
-      }
-      __logdClose(ret);
-      ret = logdOpen();
-      __android_log_unlock();
 
-      if (ret < 0) {
-        return ret;
-      }
-
-      ret = TEMP_FAILURE_RETRY(writev(atomic_load(&logdLoggerWrite.context.sock), newVec, i));
-      if (ret < 0) {
-        ret = -errno;
-      }
-      [[fallthrough]];
-    default:
-      break;
+  if (ret < 0) {
+    ret = -errno;
   }
 
   if (ret > (ssize_t)sizeof(header)) {
     ret -= sizeof(header);
-  } else if (ret == -EAGAIN) {
+  } else if (ret < 0) {
     atomic_fetch_add_explicit(&dropped, 1, memory_order_relaxed);
     if (logId == LOG_ID_SECURITY) {
       atomic_fetch_add_explicit(&droppedSecurity, 1, memory_order_relaxed);
diff --git a/liblog/pmsg_writer.cpp b/liblog/pmsg_writer.cpp
index 54980d9..de48086 100644
--- a/liblog/pmsg_writer.cpp
+++ b/liblog/pmsg_writer.cpp
@@ -25,68 +25,51 @@
 #include <sys/types.h>
 #include <time.h>
 
+#include <shared_mutex>
+
 #include <log/log_properties.h>
 #include <private/android_filesystem_config.h>
 #include <private/android_logger.h>
 
 #include "log_portability.h"
 #include "logger.h"
+#include "rwlock.h"
 #include "uio.h"
 
-static int pmsgOpen();
-static void pmsgClose();
-static int pmsgAvailable(log_id_t logId);
-static int pmsgWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr);
+static void PmsgClose();
+static int PmsgWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr);
 
 struct android_log_transport_write pmsgLoggerWrite = {
     .name = "pmsg",
     .logMask = 0,
-    .context.fd = -1,
-    .available = pmsgAvailable,
-    .open = pmsgOpen,
-    .close = pmsgClose,
-    .write = pmsgWrite,
+    .available = [](log_id_t) { return 0; },
+    .open = [] { return 0; },
+    .close = PmsgClose,
+    .write = PmsgWrite,
 };
 
-static int pmsgOpen() {
-  int fd = atomic_load(&pmsgLoggerWrite.context.fd);
-  if (fd < 0) {
-    int i;
+static int pmsg_fd;
+static RwLock pmsg_fd_lock;
 
-    fd = TEMP_FAILURE_RETRY(open("/dev/pmsg0", O_WRONLY | O_CLOEXEC));
-    i = atomic_exchange(&pmsgLoggerWrite.context.fd, fd);
-    if ((i >= 0) && (i != fd)) {
-      close(i);
-    }
+static void PmsgOpen() {
+  auto lock = std::unique_lock{pmsg_fd_lock};
+  if (pmsg_fd > 0) {
+    // Someone raced us and opened the socket already.
+    return;
   }
 
-  return fd;
+  pmsg_fd = TEMP_FAILURE_RETRY(open("/dev/pmsg0", O_WRONLY | O_CLOEXEC));
 }
 
-static void pmsgClose() {
-  int fd = atomic_exchange(&pmsgLoggerWrite.context.fd, -1);
-  if (fd >= 0) {
-    close(fd);
+static void PmsgClose() {
+  auto lock = std::unique_lock{pmsg_fd_lock};
+  if (pmsg_fd > 0) {
+    close(pmsg_fd);
   }
+  pmsg_fd = 0;
 }
 
-static int pmsgAvailable(log_id_t logId) {
-  if (logId > LOG_ID_SECURITY) {
-    return -EINVAL;
-  }
-  if ((logId != LOG_ID_SECURITY) && (logId != LOG_ID_EVENTS) && !__android_log_is_debuggable()) {
-    return -EINVAL;
-  }
-  if (atomic_load(&pmsgLoggerWrite.context.fd) < 0) {
-    if (access("/dev/pmsg0", W_OK) == 0) {
-      return 0;
-    }
-    return -EBADF;
-  }
-  return 1;
-}
-
-static int pmsgWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr) {
+static int PmsgWrite(log_id_t logId, struct timespec* ts, struct iovec* vec, size_t nr) {
   static const unsigned headerLength = 2;
   struct iovec newVec[nr + headerLength];
   android_log_header_t header;
@@ -94,17 +77,31 @@
   size_t i, payloadSize;
   ssize_t ret;
 
-  if ((logId == LOG_ID_EVENTS) && !__android_log_is_debuggable()) {
-    if (vec[0].iov_len < 4) {
-      return -EINVAL;
+  if (!__android_log_is_debuggable()) {
+    if (logId != LOG_ID_EVENTS && logId != LOG_ID_SECURITY) {
+      return -1;
     }
 
-    if (SNET_EVENT_LOG_TAG != *static_cast<uint32_t*>(vec[0].iov_base)) {
-      return -EPERM;
+    if (logId == LOG_ID_EVENTS) {
+      if (vec[0].iov_len < 4) {
+        return -EINVAL;
+      }
+
+      if (SNET_EVENT_LOG_TAG != *static_cast<uint32_t*>(vec[0].iov_base)) {
+        return -EPERM;
+      }
     }
   }
 
-  if (atomic_load(&pmsgLoggerWrite.context.fd) < 0) {
+  auto lock = std::shared_lock{pmsg_fd_lock};
+
+  if (pmsg_fd <= 0) {
+    lock.unlock();
+    PmsgOpen();
+    lock.lock();
+  }
+
+  if (pmsg_fd <= 0) {
     return -EBADF;
   }
 
@@ -158,7 +155,7 @@
   }
   pmsgHeader.len += payloadSize;
 
-  ret = TEMP_FAILURE_RETRY(writev(atomic_load(&pmsgLoggerWrite.context.fd), newVec, i));
+  ret = TEMP_FAILURE_RETRY(writev(pmsg_fd, newVec, i));
   if (ret < 0) {
     ret = errno ? -errno : -ENOTCONN;
   }
@@ -193,7 +190,6 @@
 /* Write a buffer as filename references (tag = <basedir>:<basename>) */
 ssize_t __android_log_pmsg_file_write(log_id_t logId, char prio, const char* filename,
                                       const char* buf, size_t len) {
-  bool weOpened;
   size_t length, packet_len;
   const char* tag;
   char *cp, *slash;
@@ -233,7 +229,6 @@
   vec[1].iov_base = (unsigned char*)tag;
   vec[1].iov_len = length;
 
-  weOpened = false;
   for (ts.tv_nsec = 0, length = len; length; ts.tv_nsec += ANDROID_LOG_PMSG_FILE_SEQUENCE) {
     ssize_t ret;
     size_t transfer;
@@ -254,37 +249,15 @@
     vec[2].iov_base = (unsigned char*)buf;
     vec[2].iov_len = transfer;
 
-    if (atomic_load(&pmsgLoggerWrite.context.fd) < 0) {
-      if (!weOpened) { /* Impossible for weOpened = true here */
-        __android_log_lock();
-      }
-      weOpened = atomic_load(&pmsgLoggerWrite.context.fd) < 0;
-      if (!weOpened) {
-        __android_log_unlock();
-      } else if (pmsgOpen() < 0) {
-        __android_log_unlock();
-        free(cp);
-        return -EBADF;
-      }
-    }
-
-    ret = pmsgWrite(logId, &ts, vec, sizeof(vec) / sizeof(vec[0]));
+    ret = PmsgWrite(logId, &ts, vec, sizeof(vec) / sizeof(vec[0]));
 
     if (ret <= 0) {
-      if (weOpened) {
-        pmsgClose();
-        __android_log_unlock();
-      }
       free(cp);
       return ret ? ret : (len - length);
     }
     length -= transfer;
     buf += transfer;
   }
-  if (weOpened) {
-    pmsgClose();
-    __android_log_unlock();
-  }
   free(cp);
   return len;
 }
diff --git a/liblog/rwlock.h b/liblog/rwlock.h
new file mode 100644
index 0000000..00f1806
--- /dev/null
+++ b/liblog/rwlock.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#pragma once
+
+#include <pthread.h>
+
+// As of the end of Dec 2019, std::shared_mutex is *not* simply a pthread_rwlock, but rather a
+// combination of std::mutex and std::condition variable, which is obviously less efficient.  This
+// immitates what std::shared_mutex should be doing and is compatible with std::shared_lock and
+// std::unique_lock.
+
+class RwLock {
+ public:
+  RwLock() {}
+  ~RwLock() {}
+
+  void lock() { pthread_rwlock_wrlock(&rwlock_); }
+  void unlock() { pthread_rwlock_unlock(&rwlock_); }
+
+  void lock_shared() { pthread_rwlock_rdlock(&rwlock_); }
+  void unlock_shared() { pthread_rwlock_unlock(&rwlock_); }
+
+ private:
+  pthread_rwlock_t rwlock_ = PTHREAD_RWLOCK_INITIALIZER;
+};
diff --git a/liblog/tests/Android.bp b/liblog/tests/Android.bp
index 99df4ca..f58c524 100644
--- a/liblog/tests/Android.bp
+++ b/liblog/tests/Android.bp
@@ -62,6 +62,7 @@
         "log_time_test.cpp",
         "log_wrap_test.cpp",
         "logprint_test.cpp",
+        "rwlock_test.cpp",
     ],
     shared_libs: [
         "libcutils",
diff --git a/liblog/tests/rwlock_test.cpp b/liblog/tests/rwlock_test.cpp
new file mode 100644
index 0000000..617d5c4
--- /dev/null
+++ b/liblog/tests/rwlock_test.cpp
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#include "../rwlock.h"
+
+#include <chrono>
+#include <shared_mutex>
+#include <thread>
+
+#include <gtest/gtest.h>
+
+using namespace std::literals;
+
+TEST(rwlock, reader_then_reader_lock) {
+  RwLock lock;
+
+  bool thread_ran = false;
+  auto read_guard = std::shared_lock{lock};
+
+  auto reader_thread = std::thread([&] {
+    auto read_guard = std::shared_lock{lock};
+    thread_ran = true;
+  });
+
+  auto end_time = std::chrono::steady_clock::now() + 1s;
+
+  while (std::chrono::steady_clock::now() < end_time) {
+    if (thread_ran) {
+      break;
+    }
+  }
+
+  EXPECT_EQ(true, thread_ran);
+
+  // Unlock the lock in case something went wrong, to ensure that we can still join() the thread.
+  read_guard.unlock();
+  reader_thread.join();
+}
+
+template <template <typename> typename L1, template <typename> typename L2>
+void TestBlockingLocks() {
+  RwLock lock;
+
+  bool thread_ran = false;
+  auto read_guard = L1{lock};
+
+  auto reader_thread = std::thread([&] {
+    auto read_guard = L2{lock};
+    thread_ran = true;
+  });
+
+  auto end_time = std::chrono::steady_clock::now() + 1s;
+
+  while (std::chrono::steady_clock::now() < end_time) {
+    if (thread_ran) {
+      break;
+    }
+  }
+
+  EXPECT_EQ(false, thread_ran);
+
+  read_guard.unlock();
+  reader_thread.join();
+
+  EXPECT_EQ(true, thread_ran);
+}
+
+TEST(rwlock, reader_then_writer_lock) {
+  TestBlockingLocks<std::shared_lock, std::unique_lock>();
+}
+
+TEST(rwlock, writer_then_reader_lock) {
+  TestBlockingLocks<std::unique_lock, std::shared_lock>();
+}
+
+TEST(rwlock, writer_then_writer_lock) {
+  TestBlockingLocks<std::unique_lock, std::unique_lock>();
+}