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feat(datastore): do not compress write ahead log file in case compression fails #992

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Aug 25, 2022
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feat(datastore): do not compress write ahead log file in case compression fails #992

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80 changes: 58 additions & 22 deletions server/controller/src/main/java/ai/starwhale/mlops/datastore/WalManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,8 @@ public class WalManager extends Thread {

private final int walMaxFileSize;

private final int walMaxFileSizeNoHeader;

private final String logFilePrefix;

private final int walWaitIntervalMillis;
Expand All @@ -61,6 +63,12 @@ public class WalManager extends Thread {

private final SwBuffer compressedBuffer;

private static final byte NO_COMPRESSION = 0;

private static final byte SNAPPY = 1;

private final byte[] header = new byte[]{'s', 'w', 'l', 0};

private boolean terminated;

private int logFileIndex;
Expand All @@ -77,9 +85,10 @@ public WalManager(ObjectStore objectStore,
this.bufferManager = bufferManager;
this.walFileSize = walFileSize;
this.walMaxFileSize = walMaxFileSize;
this.walMaxFileSizeNoHeader = this.walMaxFileSize - this.header.length;
this.logFilePrefix = walPrefix + "wal.log.";
this.walWaitIntervalMillis = walWaitIntervalMillis;
this.outputBuffer = this.bufferManager.allocate(this.walMaxFileSize);
this.outputBuffer = this.bufferManager.allocate(this.walMaxFileSizeNoHeader);
this.compressedBuffer = this.bufferManager.allocate(this.walMaxFileSize);
this.outputStream = new SwBufferOutputStream(this.outputBuffer);
var walMap = new TreeMap<Integer, String>();
Expand Down Expand Up @@ -143,18 +152,34 @@ private void getNext() {
log.error("fail to read from object store", e);
throw new SWProcessException(SWProcessException.ErrorType.DATASTORE);
}
if (data.capacity() < WalManager.this.header.length) {
log.error("corrupted file, size={}", data.capacity());
throw new SWProcessException(SWProcessException.ErrorType.DATASTORE);
}
int uncompressedSize;
try {
var inBuf = data.asByteBuffer();
var outBuf = this.buf.asByteBuffer();
if (inBuf.hasArray()) {
uncompressedSize = Snappy.uncompress(inBuf.array(), 0, inBuf.capacity(), outBuf.array(), 0);
} else {
uncompressedSize = Snappy.uncompress(inBuf, outBuf);
var h = new byte[4];
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data.getBytes(0, h, 0, h.length);
var compressed = data.slice(h.length, data.capacity() - h.length);
if (h[3] == NO_COMPRESSION) {
compressed.copyTo(this.buf);
uncompressedSize = compressed.capacity();
} else {
try {
var inBuf = compressed.asByteBuffer();
var outBuf = this.buf.asByteBuffer();
if (inBuf.hasArray()) {
uncompressedSize = Snappy.uncompress(inBuf.array(),
inBuf.arrayOffset(),
inBuf.capacity(),
outBuf.array(),
outBuf.arrayOffset());
} else {
uncompressedSize = Snappy.uncompress(inBuf, outBuf);
}
} catch (IOException e) {
log.error("fail to uncompress", e);
throw new SWProcessException(SWProcessException.ErrorType.DATASTORE);
}
} catch (IOException e) {
log.error("fail to uncompress", e);
throw new SWProcessException(SWProcessException.ErrorType.DATASTORE);
}
WalManager.this.bufferManager.release(data);
this.inputStream = new SwBufferInputStream(this.buf.slice(0, uncompressedSize));
Expand All @@ -163,7 +188,7 @@ private void getNext() {
}

public void append(Wal.WalEntry entry) {
if (entry.getSerializedSize() > this.walMaxFileSize) {
if (entry.getSerializedSize() > this.walMaxFileSizeNoHeader) {
for (var e : this.splitEntry(entry)) {
this.append(e);
}
Expand Down Expand Up @@ -241,7 +266,7 @@ private PopulationStatus populateOutput() {
entry = this.entries.getFirst();
}
if (CodedOutputStream.computeMessageSizeNoTag(entry) + this.outputStream.getOffset()
> this.walMaxFileSize) {
> this.walMaxFileSizeNoHeader) {
if (this.outputStream.getOffset() == 0) {
// huge single entry
log.error(
Expand Down Expand Up @@ -275,25 +300,35 @@ private void writeToObjectStore(boolean clearOutput) {
try {
var inBuf = this.outputBuffer.asByteBuffer();
var outBuf = this.compressedBuffer.asByteBuffer();
this.header[3] = WalManager.SNAPPY;
outBuf.put(header);
if (inBuf.hasArray()) {
compressedSize = Snappy.compress(inBuf.array(), 0, this.outputStream.getOffset(), outBuf.array(), 0);
compressedSize = Snappy.compress(inBuf.array(),
inBuf.arrayOffset(),
this.outputStream.getOffset(),
outBuf.array(),
outBuf.arrayOffset() + outBuf.position());
} else {
inBuf.limit(this.outputStream.getOffset());
compressedSize = Snappy.compress(inBuf, outBuf);
}
} catch (IOException e) {
log.error("data loss: failed to compress", e);
return;
log.warn("failed to compress", e);
this.header[3] = WalManager.NO_COMPRESSION;
this.compressedBuffer.setBytes(0, this.header, 0, this.header.length);
this.outputBuffer.copyTo(this.compressedBuffer.slice(4, this.outputStream.getOffset()));
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compressedSize = this.outputStream.getOffset();
}
try {
int compressedBufferSize = compressedSize + this.header.length;
Retry.decorateCheckedRunnable(
Retry.of("put", RetryConfig.custom()
.maxAttempts(10000)
.intervalFunction(IntervalFunction.ofExponentialRandomBackoff(100, 2.0, 0.5, 10000))
.retryOnException(e -> !terminated)
.build()),
() -> this.objectStore.put(this.logFilePrefix + this.logFileIndex,
this.compressedBuffer.slice(0, compressedSize)))
this.compressedBuffer.slice(0, compressedBufferSize)))
.run();
} catch (Throwable e) {
log.error("data loss: failed to write wal log", e);
Expand All @@ -314,22 +349,23 @@ private List<Wal.WalEntry> splitEntry(Wal.WalEntry entry) {
builder.setTableSchema(entry.getTableSchema());
}
int currentEntrySize = builder.build().getSerializedSize();
if (currentEntrySize > this.walMaxFileSize) {
if (currentEntrySize > this.walMaxFileSizeNoHeader) {
throw new SWValidationException(SWValidationException.ValidSubject.DATASTORE,
"schema is too large or walMaxFileSize is too small. size=" + currentEntrySize
+ " walMaxFileSize=" + this.walMaxFileSize);
+ " walMaxFileSizeNoHeader=" + this.walMaxFileSizeNoHeader);
}
for (var record : entry.getRecordsList()) {
// field number is less than 128, so simply use 1 instead
var recordSize = CodedOutputStream.computeMessageSize(1, record);
currentEntrySize += recordSize;
if (currentEntrySize + CodedOutputStream.computeUInt32SizeNoTag(currentEntrySize) > this.walMaxFileSize) {
if (currentEntrySize + CodedOutputStream.computeUInt32SizeNoTag(currentEntrySize)
> this.walMaxFileSizeNoHeader) {
ret.add(builder.build());
builder.clearTableSchema();
builder.clearRecords();
currentEntrySize = headerSize + recordSize;
if (currentEntrySize + CodedOutputStream.computeUInt32SizeNoTag(currentEntrySize)
> this.walMaxFileSize) {
> this.walMaxFileSizeNoHeader) {
throw new SWValidationException(SWValidationException.ValidSubject.DATASTORE,
"huge single record. size=" + currentEntrySize);
}
Expand All @@ -340,7 +376,7 @@ private List<Wal.WalEntry> splitEntry(Wal.WalEntry entry) {
ret.add(builder.build());
}
for (var e : ret) {
if (e.getSerializedSize() > this.walMaxFileSize) {
if (e.getSerializedSize() > this.walMaxFileSizeNoHeader) {
throw new SWProcessException(SWProcessException.ErrorType.DATASTORE,
"invalid entry size " + e.getSerializedSize());
}
Expand Down
1 change: 1 addition & 0 deletions ...r/controller/src/main/java/ai/starwhale/mlops/objectstore/impl/FileSystemObjectStore.java
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,7 @@ public void put(String name, SwBuffer buf) throws IOException {
var temp = File.createTempFile("sw_tmp", null);
try (var channel = new FileOutputStream(temp).getChannel()) {
channel.write(buf.asByteBuffer());
channel.close();
Files.move(temp.toPath(), f.toPath(), StandardCopyOption.ATOMIC_MOVE, StandardCopyOption.REPLACE_EXISTING);
} finally {
//noinspection ResultOfMethodCallIgnored
Expand Down
2 changes: 1 addition & 1 deletion server/controller/src/test/java/ai/starwhale/mlops/datastore/WalManagerTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -265,7 +265,7 @@ public void testAppendSplitSizeCalculation() throws IOException {
this.walManager = new WalManager(this.objectStore,
this.bufferManager,
256,
entry1.getSerializedSize() + CodedOutputStream.computeUInt32SizeNoTag(entry1.getSerializedSize()),
entry1.getSerializedSize() + CodedOutputStream.computeUInt32SizeNoTag(entry1.getSerializedSize()) + 4,
"test/",
10);
builder.addAllRecords(entry2.getRecordsList());
Expand Down