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Prefetcher, to read fast. #3054

Merged
merged 4 commits into from
Apr 3, 2018
Merged

Prefetcher, to read fast. #3054

merged 4 commits into from
Apr 3, 2018

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jean-philippe-martin
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The prefetcher can load data on another thread in between calls,
and it can intelligently use its existing buffer to deal with small
seeks without having to fetch again.

@jean-philippe-martin
Prefetcher, to read fast.
f1c4af4 
The prefetcher can load data on another thread in between calls,
and it can intelligently use its existing buffer to deal with small
seeks without having to fetch again.
@googlebot googlebot added the cla: yes This human has signed the Contributor License Agreement. label Mar 16, 2018
@jean-philippe-martin
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@pongad, I understand the ball is in your camp? If it isn't then please let me know what you'd like me to do before you look at this PR.

pongad
pongad reviewed Mar 27, 2018
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@jean-philippe-martin Thank you for the PR! I made a few comments. @garrettjonesgoogle @jabubake Could you also take a look?

...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java Outdated
@@ -0,0 +1,496 @@
/*
* Copyright 2016 Google LLC

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java Outdated

// statistics, for profiling
// time spent blocking the user because we're waiting on the network
public long msWaitingForData;

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java Outdated
* @param bufSize buffer size in bytes
* @param chan channel to wrap in the prefetcher
*/
public SeekableByteChannelPrefetcher(SeekableByteChannel chan, int bufSize) throws IOException {

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java Outdated
*/
public SeekableByteChannelPrefetcher(SeekableByteChannel chan, int bufSize) throws IOException {
if (chan instanceof SeekableByteChannelPrefetcher) {
throw new IllegalArgumentException("Cannot put two prefetchers on the same channel.");

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java Outdated
// if we don't already have that block and the fetching thread is idle,
// make sure it now goes looking for that block index.
private void ensureFetching(long blockIndex) {
if (null != fetching) {

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java
this.bufSize = bufSize;
}
this.open = true;
int prefetcherIndex = prefetcherCount++;

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java Outdated
fetching = full.remove(0);
fetching.resetForIndex(blockIndex);
bytesRead += bufSize;
fetching.futureBuf = exec.submit(fetching);

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@jean-philippe-martin
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In case you'd like extra eyes, @jart is familiar with this code and may be willing to help review.

@jabubake
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@frankyn FYI

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pongad commented Mar 28, 2018

I'm good with this. @jabubake Do you also want to take a look?

jart
jart reviewed Mar 28, 2018
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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java
@@ -0,0 +1,494 @@
/*
* Copyright 2018 Google LLC

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java Outdated
exec = Executors.newFixedThreadPool(1, threadFactory);
}

public String getStatistics() {

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java
.setDaemon(true)
.build();
// Single thread to ensure no concurrent access to chan.
exec = Executors.newFixedThreadPool(1, threadFactory);

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java
// Make sure the prefetching thread's name indicate what it is and
// which prefetcher it belongs to (for debugging purposes only, naturally).
String nameFormat = "nio-prefetcher-" + prefetcherIndex + "-thread-%d";
ThreadFactory threadFactory = new ThreadFactoryBuilder()

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java
*/
@Override
public SeekableByteChannel position(long newPosition) throws IOException {
if (!open) throw new ClosedChannelException();

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java Outdated
* the entity to grow to accommodate the new bytes; the values of any bytes
* between the previous end-of-file and the newly-written bytes are
* unspecified.
* <p>

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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java
.build();
// Single thread to ensure no concurrent access to chan.
exec = Executors.newFixedThreadPool(1, threadFactory);
}

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pongad
pongad reviewed Mar 28, 2018
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...ud-nio/src/main/java/com/google/cloud/storage/contrib/nio/SeekableByteChannelPrefetcher.java
* (Of course this is only worthwhile if the underlying SeekableByteChannel doesn't already
* implement prefetching).
*/
public final class SeekableByteChannelPrefetcher implements SeekableByteChannel {

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@pongad pongad merged commit 6bccbce into googleapis:master Apr 3, 2018
@jean-philippe-martin jean-philippe-martin deleted the jp_prefetcher branch April 16, 2018 18:04
@jean-philippe-martin jean-philippe-martin mentioned this pull request Oct 26, 2018
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