Method Allocate

be/src/runtime/io/data-cache.cc:242–258

Allocates a chunk of 'len' bytes in this file. The cache partition's lock 'partition_lock' must be held when calling this function. Returns the byte offset into the file for insertion. 'len' is expected to be multiples of PAGE_SIZE. Returns -1 if the file doesn't have enough space for insertion.

  // into the file for insertion. 'len' is expected to be multiples of PAGE_SIZE.
  // Returns -1 if the file doesn't have enough space for insertion.
  int64_t Allocate(int64_t len, const std::unique_lock<SpinLock>& partition_lock) {
    DCHECK(partition_lock.owns_lock());
    DCHECK_EQ(len % PAGE_SIZE, 0);
    int64_t current_offset = current_offset_.Load();
    DCHECK_EQ(current_offset % PAGE_SIZE, 0);
    // Hold the lock in shared mode to check if 'file_' is not closed already.
    kudu::shared_lock<rw_spinlock> lock(lock_.get_lock());
    if (!allow_append_ || (current_offset + len > FLAGS_data_cache_file_max_size_bytes &&
            current_offset > 0)) {
      allow_append_ = false;
      return -1;
    }
    DCHECK(file_);
    int64_t insertion_offset = current_offset;
    current_offset_.Add(len);
    return insertion_offset;
  }

  // Reads from byte offset 'offset' for 'bytes_to_read' bytes into 'buffer'.
  // Returns true iff read succeeded. Returns false on error or if the file