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Improve Synchronizer to reduce network load

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Synchronizer now bails out early when trying to find common block with
a peer. There's no need to keep searching if common block is too far
behind that a TOO_DIVERGENT result would be returned.

fetchSummariesFromCommonBlock() reworked to return a useful
SynchronizationResult directly instead of caller trying to infer
what happened based on null/empty returned list!
This commit is contained in:
catbref 2020-03-19 11:11:35 +00:00
parent 0edadaf901
commit c4643538f1
1 changed files with 34 additions and 37 deletions
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71
src/main/java/org/qortal/controller/Synchronizer.java
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@ -3,7 +3,7 @@ package org.qortal.controller;
import java.math.BigInteger; import java.math.BigInteger;
import java.text.DecimalFormat; import java.text.DecimalFormat;
import java.text.NumberFormat; import java.text.NumberFormat;
import java.util.Collections; import java.util.ArrayList;
import java.util.List; import java.util.List;
import java.util.concurrent.locks.ReentrantLock; import java.util.concurrent.locks.ReentrantLock;
import java.util.stream.Collectors; import java.util.stream.Collectors;
@ -93,18 +93,11 @@ public class Synchronizer {
peerHeight, Base58.encode(peersLastBlockSignature), peer.getChainTipData().getLastBlockTimestamp(), peerHeight, Base58.encode(peersLastBlockSignature), peer.getChainTipData().getLastBlockTimestamp(),
ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp())); ourInitialHeight, Base58.encode(ourLastBlockSignature), ourLatestBlockData.getTimestamp()));
List<BlockSummaryData> peerBlockSummaries = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight); List<BlockSummaryData> peerBlockSummaries = new ArrayList<>();
if (peerBlockSummaries == null && Controller.isStopping()) SynchronizationResult findCommonBlockResult = fetchSummariesFromCommonBlock(repository, peer, ourInitialHeight, force, peerBlockSummaries);
return SynchronizationResult.SHUTTING_DOWN; if (findCommonBlockResult != SynchronizationResult.OK)
// Logging performed by fetchSummariesFromCommonBlock() above
if (peerBlockSummaries == null) { return findCommonBlockResult;
LOGGER.info(String.format("Error while trying to find common block with peer %s", peer));
return SynchronizationResult.NO_REPLY;
}
if (peerBlockSummaries.isEmpty()) {
LOGGER.info(String.format("Failure to find common block with peer %s", peer));
return SynchronizationResult.NO_COMMON_BLOCK;
}
// First summary is common block // First summary is common block
final BlockData commonBlockData = repository.getBlockRepository().fromSignature(peerBlockSummaries.get(0).getSignature()); final BlockData commonBlockData = repository.getBlockRepository().fromSignature(peerBlockSummaries.get(0).getSignature());
@ -132,13 +125,6 @@ public class Synchronizer {
return SynchronizationResult.NOTHING_TO_DO; return SynchronizationResult.NOTHING_TO_DO;
} }
// If common block is too far behind us then we're on massively different forks so give up.
int minCommonHeight = ourInitialHeight - MAXIMUM_COMMON_DELTA;
if (!force && commonBlockHeight < minCommonHeight) {
LOGGER.info(String.format("Blockchain too divergent with peer %s", peer));
return SynchronizationResult.TOO_DIVERGENT;
}
// Unless we're doing a forced sync, we might need to compare blocks after common block // Unless we're doing a forced sync, we might need to compare blocks after common block
if (!force && ourInitialHeight > commonBlockHeight) { if (!force && ourInitialHeight > commonBlockHeight) {
// If our latest block is very old, we're very behind and should ditch our fork. // If our latest block is very old, we're very behind and should ditch our fork.
@ -332,49 +318,59 @@ public class Synchronizer {
* @throws DataException * @throws DataException
* @throws InterruptedException * @throws InterruptedException
*/ */
private List<BlockSummaryData> fetchSummariesFromCommonBlock(Repository repository, Peer peer, int ourHeight) throws DataException, InterruptedException { private SynchronizationResult fetchSummariesFromCommonBlock(Repository repository, Peer peer, int ourHeight, boolean force, List<BlockSummaryData> blockSummariesFromCommon) throws DataException, InterruptedException {
// Start by asking for a few recent block hashes as this will cover a majority of reorgs // Start by asking for a few recent block hashes as this will cover a majority of reorgs
// Failing that, back off exponentially // Failing that, back off exponentially
int step = INITIAL_BLOCK_STEP; int step = INITIAL_BLOCK_STEP;
List<BlockSummaryData> blockSummaries = null;
int testHeight = Math.max(ourHeight - step, 1); int testHeight = Math.max(ourHeight - step, 1);
BlockData testBlockData = null; BlockData testBlockData = null;
List<BlockSummaryData> blockSummariesBatch = null;
while (testHeight >= 1) { while (testHeight >= 1) {
// Are we shutting down? // Are we shutting down?
if (Controller.isStopping()) if (Controller.isStopping())
return null; return SynchronizationResult.SHUTTING_DOWN;
// Fetch our block signature at this height // Fetch our block signature at this height
testBlockData = repository.getBlockRepository().fromHeight(testHeight); testBlockData = repository.getBlockRepository().fromHeight(testHeight);
if (testBlockData == null) { if (testBlockData == null) {
// Not found? But we've locked the blockchain and height is below blockchain's tip! // Not found? But we've locked the blockchain and height is below blockchain's tip!
LOGGER.error("Failed to get block at height lower than blockchain tip during synchronization?"); LOGGER.error("Failed to get block at height lower than blockchain tip during synchronization?");
return null; return SynchronizationResult.REPOSITORY_ISSUE;
} }
// Ask for block signatures since test block's signature // Ask for block signatures since test block's signature
byte[] testSignature = testBlockData.getSignature(); byte[] testSignature = testBlockData.getSignature();
LOGGER.trace(String.format("Requesting %d summar%s after height %d", step, (step != 1 ? "ies": "y"), testHeight)); LOGGER.trace(String.format("Requesting %d summar%s after height %d", step, (step != 1 ? "ies": "y"), testHeight));
blockSummaries = this.getBlockSummaries(peer, testSignature, step); blockSummariesBatch = this.getBlockSummaries(peer, testSignature, step);
if (blockSummaries == null) if (blockSummariesBatch == null) {
// No response - give up this time // No response - give up this time
return null; LOGGER.info(String.format("Error while trying to find common block with peer %s", peer));
return SynchronizationResult.NO_REPLY;
}
LOGGER.trace(String.format("Received %s summar%s", blockSummaries.size(), (blockSummaries.size() != 1 ? "ies" : "y"))); LOGGER.trace(String.format("Received %s summar%s", blockSummariesBatch.size(), (blockSummariesBatch.size() != 1 ? "ies" : "y")));
// Empty list means remote peer is unaware of test signature OR has no new blocks after test signature // Empty list means remote peer is unaware of test signature OR has no new blocks after test signature
if (!blockSummaries.isEmpty()) if (!blockSummariesBatch.isEmpty())
// We have entries so we have found a common block // We have entries so we have found a common block
break; break;
// No blocks after genesis block? // No blocks after genesis block?
// We don't get called for a peer at genesis height so this means NO blocks in common // We don't get called for a peer at genesis height so this means NO blocks in common
if (testHeight == 1) if (testHeight == 1) {
return Collections.emptyList(); LOGGER.info(String.format("Failure to find common block with peer %s", peer));
return SynchronizationResult.NO_COMMON_BLOCK;
}
// If common block is too far behind us then we're on massively different forks so give up.
if (!force && testHeight < ourHeight - MAXIMUM_COMMON_DELTA) {
LOGGER.info(String.format("Blockchain too divergent with peer %s", peer));
return SynchronizationResult.TOO_DIVERGENT;
}
if (peer.getVersion() >= 2) { if (peer.getVersion() >= 2) {
step <<= 1; step <<= 1;
@ -389,20 +385,21 @@ public class Synchronizer {
// Prepend test block's summary as first block summary, as summaries returned are *after* test block // Prepend test block's summary as first block summary, as summaries returned are *after* test block
BlockSummaryData testBlockSummary = new BlockSummaryData(testBlockData); BlockSummaryData testBlockSummary = new BlockSummaryData(testBlockData);
blockSummaries.add(0, testBlockSummary); blockSummariesFromCommon.add(0, testBlockSummary);
blockSummariesFromCommon.addAll(blockSummariesBatch);
// Trim summaries so that first summary is common block. // Trim summaries so that first summary is common block.
// Currently we work back from the end until we hit a block we also have. // Currently we work back from the end until we hit a block we also have.
// TODO: rewrite as modified binary search! // TODO: rewrite as modified binary search!
for (int i = blockSummaries.size() - 1; i > 0; --i) { for (int i = blockSummariesFromCommon.size() - 1; i > 0; --i) {
if (repository.getBlockRepository().exists(blockSummaries.get(i).getSignature())) { if (repository.getBlockRepository().exists(blockSummariesFromCommon.get(i).getSignature())) {
// Note: index i isn't cleared: List.subList is fromIndex inclusive to toIndex exclusive // Note: index i isn't cleared: List.subList is fromIndex inclusive to toIndex exclusive
blockSummaries.subList(0, i).clear(); blockSummariesFromCommon.subList(0, i).clear();
break; break;
} }
} }
return blockSummaries; return SynchronizationResult.OK;
} }
private List<BlockSummaryData> getBlockSummaries(Peer peer, byte[] parentSignature, int numberRequested) throws InterruptedException { private List<BlockSummaryData> getBlockSummaries(Peer peer, byte[] parentSignature, int numberRequested) throws InterruptedException {