timeout.LogSuccess(UTCNow().Sub(start))
	return LockContext{ctx: newCtx, cancel: cancel}, nil
}

// Unlock - block until write lock is released.
func (di *distLockInstance) Unlock(lc LockContext) {
	if lc.cancel != nil {
		lc.cancel()
	}
	di.rwMutex.Unlock(lc.ctx)
}

// RLock - block until read lock is taken or timeout has occurred.

     *    <p>
     *    Transforms context based on 512 bits from input block starting
     *    from the offset'th byte.
     *
     *    @param    block    input sub-array.
     *    @param    offset    starting position of sub-array.
     */
    private void transform (byte[] block, int offset) {

        // encodes 64 bytes from input block into an array of 16 32-bit
        // entities. Use A as a temp var.

        length -= remainder;
        int block;
        int i = 0;
        while (i < length) {
            block = ((bytes[i++] & 0xff) << 16) | ((bytes[i++] & 0xff) << 8) |
                    (bytes[i++] & 0xff);
            buffer.append(ALPHABET.charAt(block >>> 18));
            buffer.append(ALPHABET.charAt((block >>> 12) & 0x3f));
            buffer.append(ALPHABET.charAt((block >>> 6) & 0x3f));

	var totalWritten int64

	// Write all data blocks to dst.
	for _, block := range enBlocks[:dataBlocks] {
		// Skip blocks until we have reached our offset.
		if offset >= int64(len(block)) {
			// Decrement offset.
			offset -= int64(len(block))
			continue
		}

		// Skip until offset.
		block = block[offset:]

		// Reset the offset for next iteration to read everything
		// from subsequent blocks.

typedef struct GCSFile {
  google::cloud::storage::Client gcs_client;  // owned
  bool compose;
  absl::Mutex block_cache_lock;
  std::shared_ptr<RamFileBlockCache> file_block_cache
      ABSL_GUARDED_BY(block_cache_lock);
  uint64_t block_size;  // Reads smaller than block_size will trigger a read
                        // of block_size.
  std::unique_ptr<ExpiringLRUCache<GcsFileStat>> stat_cache;

   * be removed from the execution schedule.
   */
  fun cancelAll() {
    lock.assertNotHeld()

    taskRunner.lock.withLock {
      if (cancelAllAndDecide()) {
        taskRunner.kickCoordinator(this)
      }
    }
  }

  fun shutdown() {
    lock.assertNotHeld()

    taskRunner.lock.withLock {
      shutdown = true
      if (cancelAllAndDecide()) {

### Locks

We have 3 different things that we synchronize on.

#### Http2Connection

This lock guards internal state of each connection. This lock is never held for blocking operations. That means that we acquire the lock, read or write a few fields and release the lock. No I/O and no application-layer callbacks.

#### Http2Stream

        MethodMetaData tooManyParams = method('block', classMetaData, paramTypes: ['String', 'boolean'])
        MethodMetaData notAClosure = method('block', classMetaData, paramTypes: ['String'])
        MethodMetaData noBlockProperty = method('notBlock', classMetaData, paramTypes: [Closure.class.name])
        _ * classMetaData.findProperty('block') >> blockProperty

	var bytesWritten int64
	var bufs [][]byte
	for block := startBlock; block <= endBlock; block++ {
		var blockOffset, blockLength int64
		switch {
		case startBlock == endBlock:
			blockOffset = offset % e.blockSize
			blockLength = length
		case block == startBlock:
			blockOffset = offset % e.blockSize
			blockLength = e.blockSize - blockOffset
		case block == endBlock:
			blockOffset = 0

    deps = [
        "//tensorflow/c:env",
    ],
)

cc_library(
    name = "cleanup",
    hdrs = ["cleanup.h"],
)

cc_library(
    name = "ram_file_block_cache",
    srcs = ["ram_file_block_cache.cc"],
    hdrs = ["ram_file_block_cache.h"],
    deps = [
        ":cleanup",
        "//tensorflow/c:env",
        "//tensorflow/c:logging",
        "//tensorflow/c:tf_status",