Doug Cutting commented on HADOOP-928:
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return a (unbuffered) FSDataInputStream for open(f) and a BufferedFSDataInputStream for open(f, bufferSize)
I'm not convinced we should ever return an unbuffered stream. I think the open(f) call should return a stream with the default buffer size. Note that writes that are larger than the buffer bypass the buffer, so applications that layer their own buffers on top don't pay a penalty when using a buffered stream. They might instead however use open(f, bufferSize), specifying a small buffer size, to save memory.Note also that a RAM-based FileSystem might disable buffering altogether--even when a bufferSize is specified.
make checksums optional per FileSystem
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Key: HADOOP-928
URL: https://issues.apache.org/jira/browse/HADOOP-928
Project: Hadoop
Issue Type: Improvement
Components: fs
Reporter: Doug Cutting
Assigned To: Hairong Kuang
Attachments: checksum.patch
Checksumming is currently built into the base FileSystem class. It should instead be optional, with each FileSystem implementation electing whether to use the Hadoop-provided checksum system, or to disable it, or to implement its own custom checksum system.
To implement this, a ChecksumFileSystem implementation can be provided that wraps another FileSystem implementation, implementing checksums as in Hadoop's current mandatory implementation (i.e., as a separate crc file per file that's elided from directory listings). The 'raw' FileSystem methods would be removed. FSDataInputStream and FSDataOutputStream would be made interfaces.
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Key: HADOOP-928
URL: https://issues.apache.org/jira/browse/HADOOP-928
Project: Hadoop
Issue Type: Improvement
Components: fs
Reporter: Doug Cutting
Assigned To: Hairong Kuang
Attachments: checksum.patch
Checksumming is currently built into the base FileSystem class. It should instead be optional, with each FileSystem implementation electing whether to use the Hadoop-provided checksum system, or to disable it, or to implement its own custom checksum system.
To implement this, a ChecksumFileSystem implementation can be provided that wraps another FileSystem implementation, implementing checksums as in Hadoop's current mandatory implementation (i.e., as a separate crc file per file that's elided from directory listings). The 'raw' FileSystem methods would be removed. FSDataInputStream and FSDataOutputStream would be made interfaces.
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