A lightning fast, transactional, file-based FIFO for Android and Java.
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Latest commit 65c8c7e Feb 21, 2017 @paulo-raca paulo-raca committed with f2prateek On file resize, only zero old memory chunks after header has been wri…
…tten (#132)

* On file resize, only zero old memory chunks after header has been written.

There is that very unlike corner case when things crash after the wrapped chunk has been moved to `oldFileLength`, but the header has not been updated yet, causing file corruption.

Zero-ing the old interval after the header has been written fixes this.

* Unit test for failure on expansion


Tape by Square, Inc.

Tape is a collection of queue-related classes for Android and Java.

QueueFile is a lightning-fast, transactional, file-based FIFO. Addition and removal from an instance is an O(1) operation and is atomic. Writes are synchronous; data will be written to disk before an operation returns. The underlying file is structured to survive process and even system crashes and if an I/O exception is thrown during a mutating change, the change is aborted.

NOTE: The current implementation is built for file systems that support atomic segment writes (like YAFFS). Most conventional file systems don't support this; if the power goes out while writing a segment, the segment will contain garbage and the file will be corrupt.

An ObjectQueue represents an ordering of arbitrary objects which can be backed either by the filesystem (via QueueFile) or in memory only.

TaskQueue is a special object queue which holds Tasks, objects which have a notion of being executed. Instances are managed by an external executor which prepares and executes enqueued tasks.

Some examples are available on the website.


Download the latest JAR or grab via Maven:


or Gradle:

compile 'com.squareup:tape:1.2.3'

Snapshots of the development version are available in Sonatype's snapshots repository.


Copyright 2012 Square, Inc.

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


Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.