WIP

command_line.cc

@@ -13,7 +13,6 @@
 
 #include "third_party/tiny-process-library/process.hpp"
 
-#define DOCTEST_CONFIG_IMPLEMENT
 #include "third_party/doctest/doctest/doctest.h"
 
 #include <rapidjson/istreamwrapper.h>
@@ -1026,10 +1025,6 @@ void PreMain() {
   MessageRegistry::instance()->Register<In_WorkspaceSymbolRequest>();
 }
 
-TEST_CASE("helo") {
-  CHECK(1 == 1);
-}
-
 int main(int argc, char** argv) {
   bool loop = false;
   while (loop)

doctest_impl.cc

@@ -0,0 +1,2 @@
+#define DOCTEST_CONFIG_IMPLEMENT
+#include "third_party/doctest/doctest/doctest.h"

ipc.cc

@@ -2,44 +2,48 @@
 #include "serializer.h"
 #include "utils.h"
 
+#include "third_party/doctest/doctest/doctest.h"
+
 namespace {
-  // The absolute smallest partial payload we should send. This must be >0, ie, 1 is the
-  // minimum. Keep a reasonably high value so we don't send needlessly send tiny payloads.
-  const int kMinimumPartialPayloadSize = 128;
+// The absolute smallest partial payload we should send. This must be >0, ie, 1 is the
+// minimum. Keep a reasonably high value so we don't send needlessly send tiny payloads.
+const int kMinimumPartialPayloadSize = 128;
 
-  // JSON-encoded message that is passed across shared memory.
-  //
-  // Messages are funky objects. They contain potentially variable amounts of
-  // data and are passed between processes. This means that they need to be
-  // fully relocatable, ie, it is possible to memmove them in memory to a
-  // completely different address.
-  struct JsonMessage {
-    IpcId ipc_id;
-    int partial_message_id;
-    bool has_more_chunks;
-    size_t payload_size;
-    void* payload() {
-      return reinterpret_cast<char*>(this) + sizeof(JsonMessage);
-    }
+const int kBufferSize = 1024 * 1024 * 32;  // number of chars/bytes (32mb) in the message buffer.
 
-    void Setup(IpcId ipc_id, int partial_message_id, bool has_more_chunks, size_t payload_size, const char* payload) {
-      this->ipc_id = ipc_id;
-      this->partial_message_id = partial_message_id;
-      this->has_more_chunks = has_more_chunks;
-      this->payload_size = payload_size;
-
-      char* payload_dest = reinterpret_cast<char*>(this) + sizeof(JsonMessage);
-      memcpy(payload_dest, payload, payload_size);
-    }
-  };
-
-  std::string NameToServerName(const std::string& name) {
-    return name + "server";
+// JSON-encoded message that is passed across shared memory.
+//
+// Messages are funky objects. They contain potentially variable amounts of
+// data and are passed between processes. This means that they need to be
+// fully relocatable, ie, it is possible to memmove them in memory to a
+// completely different address.
+struct JsonMessage {
+  IpcId ipc_id;
+  int partial_message_id;
+  bool has_more_chunks;
+  size_t payload_size;
+  void* payload() {
+    return reinterpret_cast<char*>(this) + sizeof(JsonMessage);
   }
 
-  std::string NameToClientName(const std::string& name, int client_id) {
-    return name + "client" + std::to_string(client_id);
+  void Setup(IpcId ipc_id, int partial_message_id, bool has_more_chunks, size_t payload_size, const char* payload) {
+    this->ipc_id = ipc_id;
+    this->partial_message_id = partial_message_id;
+    this->has_more_chunks = has_more_chunks;
+    this->payload_size = payload_size;
+
+    char* payload_dest = reinterpret_cast<char*>(this) + sizeof(JsonMessage);
+    memcpy(payload_dest, payload, payload_size);
   }
+};
+
+std::string NameToServerName(const std::string& name) {
+  return name + "server";
+}
+
+std::string NameToClientName(const std::string& name, int client_id) {
+  return name + "client" + std::to_string(client_id);
+}
 }
 
 IpcRegistry* IpcRegistry::instance_ = nullptr;
@@ -206,14 +210,14 @@ void IpcDirectionalChannel::RemoveResizableBuffer(int id) {
 }
 
 IpcDirectionalChannel::IpcDirectionalChannel(const std::string& name, bool initialize_shared_memory) {
-  shared = CreatePlatformSharedMemory(name + "memory");
+  shared = CreatePlatformSharedMemory(name + "memory", kBufferSize);
   mutex = CreatePlatformMutex(name + "mutex");
-  local = std::unique_ptr<char>(new char[shmem_size]);
+  local = std::unique_ptr<char>(new char[kBufferSize]);
 
   // TODO: connecting a client will allocate reset shared state on the
   // buffer. We need to store if we "initialized".
-  shared_buffer = MakeUnique<MessageBuffer>(shared->shared, shmem_size, initialize_shared_memory);
-  local_buffer = MakeUnique<MessageBuffer>(local.get(), shmem_size, true /*initialize*/);
+  shared_buffer = MakeUnique<MessageBuffer>(shared->data, kBufferSize, initialize_shared_memory);
+  local_buffer = MakeUnique<MessageBuffer>(local.get(), kBufferSize, true /*initialize*/);
 }
 
 IpcDirectionalChannel::~IpcDirectionalChannel() {}
@@ -249,7 +253,7 @@ void IpcDispatch(PlatformMutex* mutex, std::function<DispatchResult()> action) {
 
 void IpcDirectionalChannel::PushMessage(IpcMessage* message) {
   assert(message->ipc_id != IpcId::Invalid);
-  assert(shmem_size > sizeof(JsonMessage) + kMinimumPartialPayloadSize);
+  assert(kBufferSize > sizeof(JsonMessage) + kMinimumPartialPayloadSize);
 
   rapidjson::StringBuffer output;
   rapidjson::PrettyWriter<rapidjson::StringBuffer> writer(output);
@@ -331,8 +335,8 @@ std::vector<std::unique_ptr<IpcMessage>> IpcDirectionalChannel::TakeMessages() {
     // posting data as soon as possible.
     {
       std::unique_ptr<PlatformScopedMutexLock> lock = CreatePlatformScopedMutexLock(mutex.get());
-      assert(shared_buffer->metadata()->bytes_used <= shmem_size);
-      memcpy(local.get(), shared->shared, sizeof(MessageBuffer::Metadata) + shared_buffer->metadata()->bytes_used);
+      assert(shared_buffer->metadata()->bytes_used <= kBufferSize);
+      memcpy(local.get(), shared->data, sizeof(MessageBuffer::Metadata) + shared_buffer->metadata()->bytes_used);
       shared_buffer->metadata()->bytes_used = 0;
       shared_buffer->free_message()->ipc_id = IpcId::Invalid;
     }
@@ -383,7 +387,7 @@ std::vector<std::unique_ptr<IpcMessage>> IpcServer::TakeMessages() {
 
 IpcClient::IpcClient(const std::string& name, int client_id)
   : server_(NameToServerName(name), false /*initialize_shared_memory*/),
-    client_(NameToClientName(name, client_id), false /*initialize_shared_memory*/) {}
+  client_(NameToClientName(name, client_id), false /*initialize_shared_memory*/) {}
 
 void IpcClient::SendToServer(IpcMessage* message) {
   server_.PushMessage(message);
@@ -392,3 +396,41 @@ void IpcClient::SendToServer(IpcMessage* message) {
 std::vector<std::unique_ptr<IpcMessage>> IpcClient::TakeMessages() {
   return client_.TakeMessages();
 }
+
+
+
+
+
+template<typename T>
+struct TestIpcMessage : IpcMessage {
+  T data;
+
+  TestIpcMessage() : IpcMessage(IpcId::Test) {}
+  ~TestIpcMessage() override {}
+
+  // IpcMessage:
+  void Serialize(Writer& writer) override {
+    Reflect(writer, data);
+  }
+  void Deserialize(Reader& reader) override {
+    Reflect(reader, data);
+  }
+};
+
+#if false
+TEST_CASE("foo") {
+  IpcRegistry::instance()->Register<TestIpcMessage<std::string>>(IpcId::Test);
+
+  IpcDirectionalChannel channel0("indexertestmemory", true /*initialize_shared_memory*/);
+  IpcDirectionalChannel channel1("indexertestmemory", false /*initialize_shared_memory*/);
+
+  TestIpcMessage<std::string> m;
+  m.data = "hey there";
+
+  channel0.PushMessage(&m);
+  std::vector<std::unique_ptr<IpcMessage>> messages = channel1.TakeMessages();
+  REQUIRE(messages.size() == 1);
+  REQUIRE(messages[0]->ipc_id == m.ipc_id);
+  REQUIRE(reinterpret_cast<TestIpcMessage<std::string>*>(messages[0].get())->data == m.data);
+}
+#endif

ipc.h

@@ -9,7 +9,7 @@
 #include <rapidjson/document.h>
 #include <rapidjson/prettywriter.h>
 
-#include "platform.h"
+#include "src/platform.h"
 #include "serializer.h"
 #include "utils.h"
 
@@ -38,7 +38,9 @@ enum class IpcId : int {
   CodeLensResolveRequest,
   CodeLensResolveResponse,
   WorkspaceSymbolsRequest,
-  WorkspaceSymbolsResponse
+  WorkspaceSymbolsResponse,
+
+  Test
 };
 
 namespace std {

platform_win.cc

@@ -1,92 +0,0 @@
-#ifdef _MSC_VER
-#include "platform.h"
-
-#include <cassert>
-#include <string>
-#include <Windows.h>
-
-#include "utils.h"
-
-struct PlatformMutexWin : public PlatformMutex {
-  HANDLE raw_mutex = INVALID_HANDLE_VALUE;
-
-  PlatformMutexWin(const std::string& name) {
-    raw_mutex = CreateMutex(nullptr, false /*initial_owner*/, name.c_str());
-    assert(GetLastError() != ERROR_INVALID_HANDLE);
-  }
-
-  ~PlatformMutexWin() override {
-    ReleaseMutex(raw_mutex);
-    raw_mutex = INVALID_HANDLE_VALUE;
-  }
-};
-
-struct PlatformScopedMutexLockWin : public PlatformScopedMutexLock {
-  HANDLE raw_mutex;
-
-  PlatformScopedMutexLockWin(HANDLE raw_mutex) : raw_mutex(raw_mutex) {
-    WaitForSingleObject(raw_mutex, INFINITE);
-  }
-
-  ~PlatformScopedMutexLockWin() override {
-    ReleaseMutex(raw_mutex);
-  }
-};
-
-struct PlatformSharedMemoryWin : public PlatformSharedMemory {
-  HANDLE shmem_;
-
-  PlatformSharedMemoryWin(const std::string& name) {
-    this->name = name;
-
-    shmem_ = CreateFileMapping(
-      INVALID_HANDLE_VALUE,
-      NULL,
-      PAGE_READWRITE,
-      0,
-      shmem_size,
-      name.c_str()
-    );
-
-    shared = MapViewOfFile(shmem_, FILE_MAP_ALL_ACCESS, 0, 0, shmem_size);
-  }
-
-  ~PlatformSharedMemoryWin() override {
-    UnmapViewOfFile(shared);
-    shared = nullptr;
-  }
-};
-
-
-
-std::unique_ptr<PlatformMutex> CreatePlatformMutex(const std::string& name) {
-  return MakeUnique<PlatformMutexWin>(name);
-}
-
-std::unique_ptr<PlatformScopedMutexLock> CreatePlatformScopedMutexLock(PlatformMutex* mutex) {
-  return MakeUnique<PlatformScopedMutexLockWin>(static_cast<PlatformMutexWin*>(mutex)->raw_mutex);
-}
-
-std::unique_ptr<PlatformSharedMemory> CreatePlatformSharedMemory(const std::string& name) {
-  return MakeUnique<PlatformSharedMemoryWin>(name);
-}
-
-// See http://stackoverflow.com/a/19535628
-std::string GetWorkingDirectory() {
-  char result[MAX_PATH];
-  return std::string(result, GetModuleFileName(NULL, result, MAX_PATH));
-}
-
-/*
-// linux
-#include <string>
-#include <limits.h>
-#include <unistd.h>
-
-std::string getexepath() {
-  char result[ PATH_MAX ];
-  ssize_t count = readlink( "/proc/self/exe", result, PATH_MAX );
-  return std::string( result, (count > 0) ? count : 0 );
-}
-*/
-#endif

src/buffer.cc

@@ -0,0 +1,120 @@
+#include "buffer.h"
+
+#include <mutex>
+
+#include "platform.h"
+#include "../utils.h"
+#include "../third_party/doctest/doctest/doctest.h"
+
+namespace {
+
+struct ScopedLockLocal : public ScopedLock {
+  ScopedLockLocal(std::mutex& mutex) : guard(mutex) {}
+  std::lock_guard<std::mutex> guard;
+};
+
+struct BufferLocal : public Buffer {
+  explicit BufferLocal(size_t capacity) {
+    this->data = malloc(capacity);
+    this->capacity = capacity;
+  }
+  ~BufferLocal() override {
+    free(data);
+    data = nullptr;
+    capacity = 0;
+  }
+
+  std::unique_ptr<ScopedLock> WaitForExclusiveAccess() override {
+    return MakeUnique<ScopedLockLocal>(mutex_);
+  }
+
+  std::mutex mutex_;
+};
+
+struct ScopedLockPlatform : public ScopedLock {
+  ScopedLockPlatform(PlatformMutex* mutex)
+    : guard(CreatePlatformScopedMutexLock(mutex)) {}
+
+  std::unique_ptr<PlatformScopedMutexLock> guard;
+};
+
+struct BufferPlatform : public Buffer {
+  explicit BufferPlatform(const std::string& name, size_t capacity)
+    : memory_(CreatePlatformSharedMemory(name + "_mem", capacity)),
+      mutex_(CreatePlatformMutex(name + "_mtx")) {
+    this->data = memory_->data;
+    this->capacity = memory_->capacity;
+  }
+
+  ~BufferPlatform() override {
+    data = nullptr;
+    capacity = 0;
+  }
+
+  std::unique_ptr<ScopedLock> WaitForExclusiveAccess() override {
+    return MakeUnique<ScopedLockPlatform>(mutex_.get());
+  }
+
+  std::unique_ptr<PlatformSharedMemory> memory_;
+  std::unique_ptr<PlatformMutex> mutex_;
+};
+
+}  // namespace
+
+std::unique_ptr<Buffer> Buffer::Create(size_t capacity) {
+  return MakeUnique<BufferLocal>(capacity);
+}
+
+std::unique_ptr<Buffer> Buffer::CreateSharedBuffer(const std::string& name, size_t capacity) {
+  return MakeUnique<BufferPlatform>(name, capacity);
+}
+
+TEST_SUITE("BufferLocal");
+
+TEST_CASE("create") {
+  std::unique_ptr<Buffer> b = Buffer::Create(24);
+  REQUIRE(b->data);
+  REQUIRE(b->capacity == 24);
+
+  b = Buffer::CreateSharedBuffer("indexertest", 24);
+  REQUIRE(b->data);
+  REQUIRE(b->capacity == 24);
+}
+
+TEST_CASE("lock") {
+  auto buffers = {
+    Buffer::Create(sizeof(int)),
+    Buffer::CreateSharedBuffer("indexertest", sizeof(int))
+  };
+
+  for (auto& b : buffers) {
+    int* data = reinterpret_cast<int*>(b->data);
+    *data = 0;
+
+    std::unique_ptr<std::thread> thread;
+    {
+      auto lock = b->WaitForExclusiveAccess();
+      *data = 1;
+
+      // Start a second thread, wait until it has attempted to acquire a lock.
+      volatile bool did_read = false;
+      thread = MakeUnique<std::thread>([&did_read, &b, &data]() {
+        did_read = true;
+        auto l = b->WaitForExclusiveAccess();
+        *data = 2;
+      });
+      while (!did_read)
+        std::this_thread::sleep_for(std::chrono::milliseconds(1));
+      std::this_thread::sleep_for(std::chrono::milliseconds(1));
+
+      // Verify lock acquisition is waiting.
+      REQUIRE(*data == 1);
+    }
+
+    // Wait for thread to acquire lock, verify it writes to data.
+    thread->join();
+    REQUIRE(*data == 2);
+  }
+}
+
+TEST_SUITE_END();

src/buffer.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <memory>
+#include <string>
+
+struct ScopedLock {
+  virtual ~ScopedLock() = default;
+};
+
+// Points to a generic block of memory. Note that |data| is relocatable, ie,
+// multiple Buffer instantations may point to the same underlying block of
+// memory but the data pointer has different values.
+struct Buffer {
+  // Create a new buffer of the given capacity using process-local memory.
+  static std::unique_ptr<Buffer> Create(size_t capacity);
+  // Create a buffer pointing to memory shared across processes with the given
+  // capacity.
+  static std::unique_ptr<Buffer> CreateSharedBuffer(const std::string& name,
+                                                    size_t capacity);
+
+  virtual ~Buffer() = default;
+
+  // Acquire a lock on the buffer, ie, become the only code that can read or
+  // write to it. The lock lasts so long as the returned object is alive.
+  virtual std::unique_ptr<ScopedLock> WaitForExclusiveAccess() = 0;
+
+  void* data = nullptr;
+  size_t capacity = 0;
+};
+

src/message_queue.cc

@@ -0,0 +1,37 @@
+#include "message_queue.h"
+
+#include <cassert>
+
+struct MessageQueue::BufferMetadata {
+  // Total number of used bytes exluding the sizeof this metadata object.
+  void set_total_messages_byte_count(size_t used_bytes) {
+    total_message_bytes_ = used_bytes;
+  }
+
+  // The total number of bytes in use.
+  size_t total_bytes_used_including_metadata() {
+    return total_message_bytes_ + sizeof(BufferMetadata);
+  }
+
+  // The total number of bytes currently used for messages. This does not
+  // include the sizeof the buffer metadata.
+  size_t total_message_bytes() {
+    return total_message_bytes_;
+  }
+
+private:
+  size_t total_message_bytes_ = 0;
+};
+
+MessageQueue::MessageQueue(std::unique_ptr<Buffer> buffer, bool buffer_has_data) : buffer_(std::move(buffer)) {
+  if (!buffer_has_data)
+    new(buffer_->data) BufferMetadata();
+}
+
+void MessageQueue::Enqueue(const Message& message) {
+
+}
+
+MessageQueue::BufferMetadata* MessageQueue::Metadata() {
+  return reinterpret_cast<BufferMetadata*>(buffer_->data);
+}

src/message_queue.h

@@ -0,0 +1,75 @@
+#pragma once
+
+#include <vector>
+#include <memory>
+
+#include "buffer.h"
+
+struct Message {
+  // Unique message identifier.
+  uint8_t message_id;
+
+  // Total size of the message (including metadata that this object stores).
+  size_t total_size;
+};
+
+// A MessageQueue is a FIFO container storing messages in an arbitrary memory
+// buffer.
+//  - Multiple separate MessageQueues instantiations can point to the
+//    same underlying buffer
+//  - Buffer is fully relocatable, ie, it can have multiple different
+//    addresses (as is the case for memory shared across processes).
+struct MessageQueue {
+  // Create a new MessageQueue using |buffer| as the backing data storage.
+  // This does *not* take ownership over the memory stored in |buffer|.
+  // 
+  // If |buffer_has_data| is true, then it is assumed that |buffer| contains
+  // data and has already been initialized. It is a perfectly acceptable
+  // use-case to have multiple completely separate MessageQueue
+  // instantiations pointing to the same memory.
+  explicit MessageQueue(std::unique_ptr<Buffer> buffer, bool buffer_has_data);
+  MessageQueue(const MessageQueue&) = delete;
+
+  // Enqueue a message to the queue. This will wait until there is room in
+  // queue. If the message is too large to fit into the queue, this will
+  // wait until the message has been fully sent, which may involve multiple
+  // IPC roundtrips (ie, Enqueue -> DequeueAll -> Enqueue) - so this method
+  // may take a long time to run.
+  //
+  // TODO: Consider copying message memory to a temporary buffer and running
+  // enqueues on a worker thread.
+  void Enqueue(const Message& message);
+
+  // Take all messages from the queue.
+  //
+  // note:
+  //  We could make this allocation free by returning raw pointers to the
+  //  internal process-local buffer, but that is pretty haphazard and likely
+  //  to cause a very confusing crash. The extra memory allocations here from
+  //  unique_ptr going to make a performance difference.
+  std::vector<std::unique_ptr<Message>> DequeueAll();
+
+  // Take the first available message from the queue.
+  std::unique_ptr<Message> DequeueFirst();
+
+private:
+  struct BufferMetadata;
+
+  BufferMetadata* Metadata();
+
+  std::unique_ptr<Buffer> buffer_;
+};
+
+
+/*
+// TODO: We convert IpcMessage <-> Message as a user-level operation.
+// MessageQueue doesn't know about IpcMessage.
+struct IpcMessage {
+  std::unique_ptr<Message> ToMessage();
+  void BuildFromMessage(std::unique_ptr<Message> message);
+
+  // Serialize/deserialize the message.
+  virtual void Serialize(Writer& writer) = 0;
+  virtual void Deserialize(Reader& reader) = 0;
+};
+*/

src/platform.cc

@@ -0,0 +1,39 @@
+#include "platform.h"
+
+#include <thread>
+
+#include "../third_party/doctest/doctest/doctest.h"
+
+
+TEST_SUITE("Platform");
+
+
+TEST_CASE("Mutex lock/unlock (single process)") {
+  auto m1 = CreatePlatformMutex("indexer-platformmutexttest");
+  auto l1 = CreatePlatformScopedMutexLock(m1.get());
+  auto m2 = CreatePlatformMutex("indexer-platformmutexttest");
+
+  int value = 0;
+
+  volatile bool did_run = false;
+  std::thread t([&]() {
+    did_run = true;
+    auto l2 = CreatePlatformScopedMutexLock(m2.get());
+    value = 1;
+  });
+  while (!did_run)
+    std::this_thread::sleep_for(std::chrono::milliseconds(1));
+  std::this_thread::sleep_for(std::chrono::milliseconds(1));
+
+  // Other thread has had a chance to run, but it should not have
+  // written to value yet (ie, it should be waiting).
+  REQUIRE(value == 0);
+
+  // Release the lock, wait for other thread to finish. Verify it
+  // wrote the expected value.
+  l1.reset();
+  t.join();
+  REQUIRE(value == 1);
+}
+
+TEST_SUITE_END();

src/platform.h

@@ -11,14 +11,13 @@ struct PlatformScopedMutexLock {
 };
 struct PlatformSharedMemory {
   virtual ~PlatformSharedMemory() {}
-  void* shared;
+  void* data;
+  size_t capacity;
   std::string name;
 };
 
-const int shmem_size = 1024 * 1024 * 32;  // number of chars/bytes (32mb)
-
 std::unique_ptr<PlatformMutex> CreatePlatformMutex(const std::string& name);
 std::unique_ptr<PlatformScopedMutexLock> CreatePlatformScopedMutexLock(PlatformMutex* mutex);
-std::unique_ptr<PlatformSharedMemory> CreatePlatformSharedMemory(const std::string& name);
+std::unique_ptr<PlatformSharedMemory> CreatePlatformSharedMemory(const std::string& name, size_t size);
 
 std::string GetWorkingDirectory();

src/platform_linux.cc

@@ -1,3 +1,4 @@
+#if defined(__linux__) || defined(__APPLE__)
 #include "platform.h"
 
 #include "utils.h"
@@ -123,3 +124,4 @@ std::unique_ptr<PlatformSharedMemory> CreatePlatformSharedMemory(const std::stri
   std::string name2 = "/" + name;
   return MakeUnique<PlatformSharedMemoryLinux>(name2);
 }
+#endif

src/platform_win.cc

@@ -0,0 +1,113 @@
+#if defined(_WIN32)
+#include "platform.h"
+
+#include <cassert>
+#include <iostream>
+#include <string>
+#include <Windows.h>
+
+#include "../utils.h"
+
+namespace {
+
+DWORD CheckForError(std::vector<DWORD> allow) {
+  DWORD error = GetLastError();
+  if (error == ERROR_SUCCESS || std::find(allow.begin(), allow.end(), error) != allow.end())
+    return error;
+
+  // See http://stackoverflow.com/a/17387176
+  LPSTR message_buffer = nullptr;
+  size_t size = FormatMessageA(
+    FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+    NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&message_buffer, 0, NULL);
+  std::string message(message_buffer, size);
+  LocalFree(message_buffer);
+
+  std::cerr << "Windows error code=" << error << ", message=" << message << std::endl;
+  assert(false); // debugger break
+  exit(1);
+}
+
+struct PlatformMutexWin : public PlatformMutex {
+  HANDLE raw_mutex = INVALID_HANDLE_VALUE;
+
+  PlatformMutexWin(const std::string& name) {
+    std::cerr << "[win] Creating mutex with name " << name << std::endl;
+    raw_mutex = CreateMutex(nullptr, false /*initial_owner*/, name.c_str());
+    CheckForError({ ERROR_ALREADY_EXISTS });
+  }
+
+  ~PlatformMutexWin() override {
+    CloseHandle(raw_mutex);
+    CheckForError({} /*allow*/);
+    raw_mutex = INVALID_HANDLE_VALUE;
+  }
+};
+
+struct PlatformScopedMutexLockWin : public PlatformScopedMutexLock {
+  HANDLE raw_mutex;
+
+  PlatformScopedMutexLockWin(HANDLE raw_mutex) : raw_mutex(raw_mutex) {
+    DWORD result = WaitForSingleObject(raw_mutex, INFINITE);
+    assert(result != WAIT_FAILED);
+    CheckForError({} /*allow*/);
+  }
+
+  ~PlatformScopedMutexLockWin() override {
+    ReleaseMutex(raw_mutex);
+    CheckForError({} /*allow*/);
+  }
+};
+
+struct PlatformSharedMemoryWin : public PlatformSharedMemory {
+  HANDLE shmem_;
+
+  PlatformSharedMemoryWin(const std::string& name, size_t capacity) {
+    std::cerr << "[win] Creating shared memory with name " << name << " and capacity " << capacity << std::endl;
+    this->name = name;
+
+    shmem_ = CreateFileMapping(
+      INVALID_HANDLE_VALUE,
+      NULL,
+      PAGE_READWRITE,
+      0,
+      capacity,
+      name.c_str()
+    );
+    CheckForError({ ERROR_ALREADY_EXISTS } /*allow*/);
+
+    data = MapViewOfFile(shmem_, FILE_MAP_ALL_ACCESS, 0, 0, capacity);
+    CheckForError({ ERROR_ALREADY_EXISTS } /*allow*/);
+
+    this->capacity = capacity;
+  }
+
+  ~PlatformSharedMemoryWin() override {
+    UnmapViewOfFile(data);
+    CheckForError({} /*allow*/);
+
+    data = nullptr;
+    capacity = 0;
+  }
+};
+
+}  // namespace
+
+std::unique_ptr<PlatformMutex> CreatePlatformMutex(const std::string& name) {
+  return MakeUnique<PlatformMutexWin>(name);
+}
+
+std::unique_ptr<PlatformScopedMutexLock> CreatePlatformScopedMutexLock(PlatformMutex* mutex) {
+  return MakeUnique<PlatformScopedMutexLockWin>(static_cast<PlatformMutexWin*>(mutex)->raw_mutex);
+}
+
+std::unique_ptr<PlatformSharedMemory> CreatePlatformSharedMemory(const std::string& name, size_t size) {
+  return MakeUnique<PlatformSharedMemoryWin>(name, size);
+}
+
+// See http://stackoverflow.com/a/19535628
+std::string GetWorkingDirectory() {
+  char result[MAX_PATH];
+  return std::string(result, GetModuleFileName(NULL, result, MAX_PATH));
+}
+#endif

src/resizable_buffer.cc

@@ -0,0 +1,100 @@
+#include "resizable_buffer.h"
+
+#include "../third_party/doctest/doctest/doctest.h"
+
+#include <cassert>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+
+namespace {
+const size_t kInitialCapacity = 128;
+}
+
+ResizableBuffer::ResizableBuffer() {
+  buffer = malloc(kInitialCapacity);
+  size = 0;
+  capacity_ = kInitialCapacity;
+}
+
+ResizableBuffer::~ResizableBuffer() {
+  free(buffer);
+  size = 0;
+  capacity_ = 0;
+}
+
+void ResizableBuffer::Append(void* content, size_t content_size) {
+  assert(capacity_ >= 0);
+
+  size_t new_size = size + content_size;
+  
+  // Grow buffer capacity if needed.
+  if (new_size >= capacity_) {
+    size_t new_capacity = capacity_ * 2;
+    while (new_size >= new_capacity)
+      new_capacity *= 2;
+    void* new_memory = malloc(new_capacity);
+    assert(size < capacity_);
+    memcpy(new_memory, buffer, size);
+    free(buffer);
+    buffer = new_memory;
+    capacity_ = new_capacity;
+  }
+
+  // Append new content into memory.
+  memcpy(reinterpret_cast<uint8_t*>(buffer) + size, content, content_size);
+  size = new_size;
+}
+
+void ResizableBuffer::Reset() {
+  size = 0;
+}
+
+TEST_SUITE("ResizableBuffer");
+
+TEST_CASE("buffer starts with zero size") {
+  ResizableBuffer b;
+  REQUIRE(b.buffer);
+  REQUIRE(b.size == 0);
+}
+
+TEST_CASE("append and reset") {
+  int content = 1;
+  ResizableBuffer b;
+
+  b.Append(&content, sizeof(content));
+  REQUIRE(b.size == sizeof(content));
+
+  b.Append(&content, sizeof(content));
+  REQUIRE(b.size == (2 * sizeof(content)));
+
+  b.Reset();
+  REQUIRE(b.size == 0);
+}
+
+TEST_CASE("appended content is copied into buffer w/ resize") {
+  int content = 0;
+  ResizableBuffer b;
+
+  // go past kInitialCapacity to verify resize works too
+  while (b.size < kInitialCapacity * 2) {
+    b.Append(&content, sizeof(content));
+    content += 1;
+  }
+
+  for (int i = 0; i < content; ++i)
+    REQUIRE(i == *(reinterpret_cast<int*>(b.buffer) + i));
+}
+
+TEST_CASE("reset does not reallocate") {
+  ResizableBuffer b;
+
+  while (b.size < kInitialCapacity)
+    b.Append(&b, sizeof(b));
+  
+  void* buffer = b.buffer;
+  b.Reset();
+  REQUIRE(b.buffer == buffer);
+}
+
+TEST_SUITE_END();

src/resizable_buffer.h

@@ -0,0 +1,21 @@
+#pragma once
+
+// Points to a generic block of memory that can be resized. This class owns
+// and has the only pointer to the underlying memory buffer.
+struct ResizableBuffer {
+  ResizableBuffer();
+  ResizableBuffer(const ResizableBuffer&) = delete;
+  ~ResizableBuffer();
+
+  void Append(void* content, size_t content_size);
+  void Reset();
+
+  // Buffer content.
+  void* buffer;
+  // Number of bytes in |buffer|. Note that the actual buffer may be larger
+  // than |size|.
+  size_t size;
+
+private:
+  size_t capacity_;
+};

test.cc

@@ -3,7 +3,7 @@
 #include "indexer.h"
 #include "serializer.h"
 #include "utils.h"
-#include "platform.h"
+#include "src/platform.h"
 
 void Write(const std::vector<std::string>& strs) {
   for (const std::string& str : strs)