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/*******************************************************************************
* Copyright 2011 Netflix
*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
******************************************************************************/
package com.netflix.astyanax.recipes.reader;
import java.io.Flushable;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.base.Function;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import com.netflix.astyanax.Keyspace;
import com.netflix.astyanax.connectionpool.TokenRange;
import com.netflix.astyanax.connectionpool.exceptions.ConnectionException;
import com.netflix.astyanax.model.ColumnFamily;
import com.netflix.astyanax.model.ColumnSlice;
import com.netflix.astyanax.model.ConsistencyLevel;
import com.netflix.astyanax.model.Row;
import com.netflix.astyanax.model.Rows;
import com.netflix.astyanax.partitioner.BigInteger127Partitioner;
import com.netflix.astyanax.partitioner.Partitioner;
import com.netflix.astyanax.query.CheckpointManager;
import com.netflix.astyanax.query.ColumnFamilyQuery;
import com.netflix.astyanax.query.RowSliceQuery;
import com.netflix.astyanax.retry.RetryPolicy;
import com.netflix.astyanax.shallows.EmptyCheckpointManager;
/**
* Recipe that is used to read all rows from a column family.
*
* @author elandau
*
* @param
* @param
*/
public class AllRowsReader implements Callable {
private static final Logger LOG = LoggerFactory.getLogger(AllRowsReader.class);
private static final Partitioner DEFAULT_PARTITIONER = BigInteger127Partitioner.get();
private final static int DEFAULT_PAGE_SIZE = 100;
private final Keyspace keyspace;
private final ColumnFamily columnFamily;
private final int pageSize;
private final Integer concurrencyLevel; // Default to null will force ring describe
private final ExecutorService executor;
private final CheckpointManager checkpointManager;
private final Function, Boolean> rowFunction;
private final Function, Boolean> rowsFunction;
private final boolean repeatLastToken;
private final ColumnSlice columnSlice;
private final String startToken;
private final String endToken;
private final Boolean includeEmptyRows; // Default to null will discard tombstones
private final List> futures = Lists.newArrayList();
private final AtomicBoolean cancelling = new AtomicBoolean(false);
private final Partitioner partitioner;
private final ConsistencyLevel consistencyLevel;
private final RetryPolicy retryPolicy;
private AtomicReference error = new AtomicReference();
private String dc;
private String rack;
public static class Builder {
private final Keyspace keyspace;
private final ColumnFamily columnFamily;
private Partitioner partitioner = DEFAULT_PARTITIONER;
private int pageSize = DEFAULT_PAGE_SIZE;
private Integer concurrencyLevel; // Default to null will force ring describe
private ExecutorService executor;
private CheckpointManager checkpointManager = new EmptyCheckpointManager();
private Function, Boolean> rowFunction;
private Function, Boolean> rowsFunction;
private boolean repeatLastToken = true;
private ColumnSlice columnSlice;
private String startToken;
private String endToken;
private Boolean includeEmptyRows; // Default to null will discard tombstones
private String dc;
private String rack;
private ConsistencyLevel consistencyLevel = null;
private RetryPolicy retryPolicy;
public Builder(Keyspace ks, ColumnFamily columnFamily) {
this.keyspace = ks;
this.columnFamily = columnFamily;
}
/**
* Maximum number of rows to return for each incremental query to Cassandra.
* This limit also represents the page size when paginating.
*
* @param blockSize
* @return
*/
public Builder withPageSize(int pageSize) {
this.pageSize = pageSize;
return this;
}
/**
* Use this checkpoint manager to keep track of progress as all rows are being iterated
* @param manager
* @return
*/
public Builder withCheckpointManager(CheckpointManager checkpointManager) {
this.checkpointManager = checkpointManager;
return this;
}
/**
* If true will repeat the last token in the previous block when calling cassandra. This
* feature is off by default and is used to handle situations where different row keys map
* to the same token value and they are split on a page boundary. The may not be efficient
* since it requires the entire row data to be fetched (based on the column slice)
*
* @param repeatLastToken
* @return
*/
public Builder withRepeatLastToken(boolean repeatLastToken) {
this.repeatLastToken = repeatLastToken;
return this;
}
/**
* Specify a non-contiguous set of columns to retrieve.
*
* @param columns
* @return
*/
public Builder withColumnSlice(C... columns) {
this.columnSlice = new ColumnSlice(ImmutableList.copyOf(columns));
return this;
}
/**
* Specify a non-contiguous set of columns to retrieve.
*
* @param columns
* @return
*/
public Builder withColumnSlice(Collection columns) {
this.columnSlice = new ColumnSlice(columns);
return this;
}
/**
* Use this when your application caches the column slice.
*
* @param slice
* @return
*/
public Builder withColumnSlice(ColumnSlice columns) {
this.columnSlice = columns;
return this;
}
/**
* Specify a range of columns to return.
*
* @param startColumn
* First column in the range
* @param endColumn
* Last column in the range
* @param reversed
* True if the order should be reversed. Note that for reversed,
* startColumn should be greater than endColumn.
* @param count
* Maximum number of columns to return (similar to SQL LIMIT)
* @return
*/
public Builder withColumnRange(C startColumn, C endColumn, boolean reversed, int count) {
this.columnSlice = new ColumnSlice(startColumn, endColumn).setReversed(reversed).setLimit(count);
return this;
}
/**
* Split the query into N threads with each thread processing an equal size chunk from the token range.
*
* Note that the actual number of threads is still limited by the available threads in the thread
* pool that was set with the AstyanaxConfiguration.
*
* @param numberOfThreads
* @return
*/
public Builder withConcurrencyLevel(int concurrencyLevel) {
Preconditions.checkArgument(concurrencyLevel >= 1, "Concurrency level must be >= 1");
this.concurrencyLevel = concurrencyLevel;
return this;
}
/**
* Use the specific executor for executing the tasks. Note that this should be used with care
* when specifying the withConcurrencyLevel.
* e.g if you have a concurrencyLevel of 10 with a fixed threadpool of size 1 then this effectively
* negates the point of the concurrencyLevel
*
* @param executor
* @return
*/
public Builder withExecutor(ExecutorService executor) {
Preconditions.checkArgument(executor != null, "Supplied executor must not be null");
this.executor = executor;
return this;
}
/**
* Execute the operation on a specific token range, instead of the entire range.
* Use this only is combination with setConcurrencyLevel being called otherwise
* it currently will not have any effect on the query. When using forTokenRange
* the specified token range will still be split into the number of threads
* specified by setConcurrencyLevel
*
* @param startToken
* @param endToken
* @return
*/
public Builder withTokenRange(BigInteger startToken, BigInteger endToken) {
this.startToken = startToken.toString();
this.endToken = endToken.toString();
return this;
}
public Builder withTokenRange(String startToken, String endToken) {
this.startToken = startToken;
this.endToken = endToken;
return this;
}
/**
* Partitioner used to determine token ranges and how to break token ranges
* into sub parts. The default is BigInteger127Partitioner which is the
* RandomPartitioner in cassandra.
*
* @param partitioner
* @return
*/
public Builder withPartitioner(Partitioner partitioner) {
this.partitioner = partitioner;
return this;
}
/**
* The default behavior is to exclude empty rows, other than when specifically asking
* for no columns back. Setting this to true will result in the row callback function
* being called for empty rows.
* @param flag
* @return
*/
public Builder withIncludeEmptyRows(Boolean flag) {
this.includeEmptyRows = flag;
return this;
}
/**
* Specify the callback function for each row being read. This callback must
* be implemented in a thread safe manner since it will be called by multiple
* internal threads.
* @param rowFunction
* @return
*/
public Builder forEachRow(Function, Boolean> rowFunction) {
this.rowFunction = rowFunction;
return this;
}
public Builder forEachPage(Function, Boolean> rowsFunction) {
this.rowsFunction = rowsFunction;
return this;
}
public Builder withConsistencyLevel(ConsistencyLevel consistencyLevel) {
this.consistencyLevel = consistencyLevel;
return this;
}
/**
* Specify dc to use when auto determining the token ranges to ensure that only ranges
* in the current dc are used.
* @param rack
* @return
*/
public Builder withDc(String dc) {
this.dc = dc;
return this;
}
/**
* Specify rack to use when auto determining the token ranges to ensure that only ranges
* in the current rack are used.
* @param rack
* @return
*/
public Builder withRack(String rack) {
this.rack = rack;
return this;
}
public Builder withRetryPolicy(RetryPolicy policy) {
this.retryPolicy = policy;
return this;
}
public AllRowsReader build() {
if (partitioner == null) {
try {
partitioner = keyspace.getPartitioner();
} catch (ConnectionException e) {
throw new RuntimeException("Unable to determine partitioner", e);
}
}
return new AllRowsReader(keyspace,
columnFamily,
concurrencyLevel,
executor,
checkpointManager,
rowFunction,
rowsFunction,
columnSlice,
startToken,
endToken,
includeEmptyRows,
pageSize,
repeatLastToken,
partitioner,
dc,
rack,
consistencyLevel,
retryPolicy);
}
}
public AllRowsReader(Keyspace keyspace, ColumnFamily columnFamily,
Integer concurrencyLevel,
ExecutorService executor,
CheckpointManager checkpointManager,
Function, Boolean> rowFunction,
Function, Boolean> rowsFunction,
ColumnSlice columnSlice,
String startToken,
String endToken,
Boolean includeEmptyRows,
int pageSize,
boolean repeatLastToken,
Partitioner partitioner,
String dc,
String rack,
ConsistencyLevel consistencyLevel,
RetryPolicy retryPolicy) {
super();
this.keyspace = keyspace;
this.columnFamily = columnFamily;
this.concurrencyLevel = concurrencyLevel;
this.executor = executor;
this.checkpointManager = checkpointManager;
this.rowFunction = rowFunction;
this.rowsFunction = rowsFunction;
this.columnSlice = columnSlice;
this.startToken = startToken;
this.endToken = endToken;
this.pageSize = pageSize;
this.repeatLastToken = repeatLastToken;
this.partitioner = partitioner;
this.dc = dc;
this.rack = rack;
this.consistencyLevel = consistencyLevel;
this.retryPolicy = retryPolicy;
// Flag explicitly set
if (includeEmptyRows != null)
this.includeEmptyRows = includeEmptyRows;
// Asking for a column range of size 0
else if (columnSlice != null && columnSlice.getColumns() == null && columnSlice.getLimit() == 0)
this.includeEmptyRows = true;
// Default to false
else
this.includeEmptyRows = false;
}
private ColumnFamilyQuery prepareQuery() {
ColumnFamilyQuery query = keyspace.prepareQuery(columnFamily);
if (consistencyLevel != null)
query.setConsistencyLevel(consistencyLevel);
if (retryPolicy != null)
query.withRetryPolicy(retryPolicy);
return query;
}
private Callable makeTokenRangeTask(final String startToken, final String endToken) {
return new Callable() {
@Override
public Boolean call() {
try {
String currentToken;
try {
currentToken = checkpointManager.getCheckpoint(startToken);
if (currentToken == null) {
currentToken = startToken;
}
else if (currentToken.equals(endToken)) {
return true;
}
} catch (Exception e) {
error.compareAndSet(null, e);
LOG.error("Failed to get checkpoint for startToken " + startToken, e);
cancel();
throw new RuntimeException("Failed to get checkpoint for startToken " + startToken, e);
}
int localPageSize = pageSize;
int rowsToSkip = 0;
while (!cancelling.get()) {
RowSliceQuery query = prepareQuery().getKeyRange(null, null, currentToken, endToken, localPageSize);
if (columnSlice != null)
query.withColumnSlice(columnSlice);
Rows rows = query.execute().getResult();
if (!rows.isEmpty()) {
try {
if (rowsFunction != null) {
if (!rowsFunction.apply(rows)) {
cancel();
return false;
}
}
else {
// Iterate through all the rows and notify the callback function
for (Row row : rows) {
if (cancelling.get())
break;
// When repeating the last row, rows to skip will be > 0
// We skip the rows that were repeated from the previous query
if (rowsToSkip > 0) {
rowsToSkip--;
continue;
}
if (!includeEmptyRows && (row.getColumns() == null || row.getColumns().isEmpty()))
continue;
if (!rowFunction.apply(row)) {
cancel();
return false;
}
}
}
}
catch (Exception e) {
error.compareAndSet(null, e);
LOG.warn(e.getMessage(), e);
cancel();
throw new RuntimeException("Error processing row", e);
}
// Get the next block
if (rows.size() == localPageSize) {
Row lastRow = rows.getRowByIndex(rows.size() - 1);
String lastToken = partitioner.getTokenForKey(lastRow.getRawKey());
checkpointManager.trackCheckpoint(startToken, currentToken);
if (repeatLastToken) {
// Start token is non-inclusive
currentToken = partitioner.getTokenMinusOne(lastToken);
// Determine the number of rows to skip in the response. Since we are repeating the
// last token it's possible (although unlikely) that there is more than one key mapping to the
// token. We therefore count backwards the number of keys that have the same token and skip
// that number in the next iteration of the loop. If, for example, 3 keys matched but only 2 were
// returned in this iteration then the first 2 keys will be skipped from the next response.
rowsToSkip = 1;
for (int i = rows.size() - 2; i >= 0; i--, rowsToSkip++) {
if (!lastToken.equals(partitioner.getTokenForKey(rows.getRowByIndex(i).getRawKey()))) {
break;
}
}
if (rowsToSkip == localPageSize) {
localPageSize++;
}
}
else {
currentToken = lastToken;
}
continue;
}
}
// We're done!
checkpointManager.trackCheckpoint(startToken, endToken);
return true;
}
cancel();
return false;
} catch (Exception e) {
error.compareAndSet(null, e);
LOG.error("Error process token/key range", e);
cancel();
throw new RuntimeException("Error process token/key range", e);
}
}
};
}
/**
* Main execution block for the all rows query.
*/
@Override
public Boolean call() throws Exception {
error.set(null);
List> subtasks = Lists.newArrayList();
// We are iterating the entire ring using an arbitrary number of threads
if (this.concurrencyLevel != null || startToken != null|| endToken != null) {
List tokens = partitioner.splitTokenRange(
startToken == null ? partitioner.getMinToken() : startToken,
endToken == null ? partitioner.getMinToken() : endToken,
this.concurrencyLevel == null ? 1 : this.concurrencyLevel);
for (TokenRange range : tokens) {
subtasks.add(makeTokenRangeTask(range.getStartToken(), range.getEndToken()));
}
}
// We are iterating through each token range
else {
List ranges = keyspace.describeRing(dc, rack);
for (TokenRange range : ranges) {
if (range.getStartToken().equals(range.getEndToken()))
subtasks.add(makeTokenRangeTask(range.getStartToken(), range.getEndToken()));
else
subtasks.add(makeTokenRangeTask(partitioner.getTokenMinusOne(range.getStartToken()), range.getEndToken()));
}
}
try {
// Use a local executor
if (executor == null) {
ExecutorService localExecutor = Executors
.newFixedThreadPool(subtasks.size(),
new ThreadFactoryBuilder().setDaemon(true)
.setNameFormat("AstyanaxAllRowsReader-%d")
.build());
try {
futures.addAll(startTasks(localExecutor, subtasks));
return waitForTasksToFinish();
}
finally {
localExecutor.shutdownNow();
}
}
// Use an externally provided executor
else {
futures.addAll(startTasks(executor, subtasks));
return waitForTasksToFinish();
}
}
catch (Exception e) {
error.compareAndSet(null, e);
LOG.warn("AllRowsReader terminated. " + e.getMessage(), e);
cancel();
throw error.get();
}
}
/**
* Wait for all tasks to finish.
*
* @param futures
* @return true if all tasks returned true or false otherwise.
*/
private boolean waitForTasksToFinish() throws Exception {
Boolean succeeded = true;
// Tracking state for multiple exceptions, if any
List stackTraces = new ArrayList();
StringBuilder sb = new StringBuilder();
int exCount = 0;
for (Future future : futures) {
try {
if (!future.get()) {
cancel();
succeeded = false;
}
}
catch (Exception e) {
error.compareAndSet(null, e);
cancel();
succeeded = false;
exCount++;
sb.append("ex" + exCount + ": ").append(e.getMessage()).append("\n");
StackTraceElement[] stackTrace = e.getStackTrace();
if (stackTrace != null && stackTrace.length > 0) {
StackTraceElement delimiterSE = new StackTraceElement("StackTrace: ex" + exCount, "", "", 0);
stackTraces.add(delimiterSE);
for (StackTraceElement se : stackTrace) {
stackTraces.add(se);
}
}
}
}
if (this.rowFunction instanceof Flushable) {
((Flushable)rowFunction).flush();
}
if (exCount > 0) {
String exMessage = sb.toString();
StackTraceElement[] seArray = stackTraces.toArray(new StackTraceElement[stackTraces.size()]);
Exception ex = new Exception(exMessage);
ex.setStackTrace(seArray);
throw ex;
}
return succeeded;
}
/**
* Submit all the callables to the executor by synchronize their execution so they all start
* AFTER the have all been submitted.
* @param executor
* @param callables
* @return
*/
private List> startTasks(ExecutorService executor, List> callables) {
List> tasks = Lists.newArrayList();
for (Callable callable : callables) {
tasks.add(executor.submit(callable));
}
return tasks;
}
/**
* Cancel all pending range iteration tasks. This will cause all internal threads to exit and
* call() to return false.
*/
public synchronized void cancel() {
cancelling.compareAndSet(false, true);
}
}
