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Simplify semantics of ChainStateFlushed callback

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Previously, ChainStateFlushed would fire either if a full flush
completed (which can happen due to memory limits, forced flush, or
on its own DATABASE_WRITE_INTERVAL timer) *or* on a
ChainStateFlushed-specific DATABASE_WRITE_INTERVAL timer. This is
both less clear for clients (as there are no guarantees about a
flush having actually happened prior to the call), and reults in
extra flushes not clearly intended by the code. We drop the second
case, providing a strong guarantee without removing the periodit
timer-based flushing.
This commit is contained in:
Matt Corallo 2018-04-27 14:08:39 -04:00
parent 50b6533aa2
commit 9cb6cdc59f
2 changed files with 17 additions and 10 deletions
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16
src/validation.cpp
View file

@ -2066,13 +2066,12 @@ bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &
LOCK(cs_main);
static int64_t nLastWrite = 0;
static int64_t nLastFlush = 0;
static int64_t nLastSetChain = 0;
std::set<int> setFilesToPrune;
bool fFlushForPrune = false;
bool fDoFullFlush = false;
int64_t nNow = 0;
bool full_flush_completed = false;
try {
{
bool fFlushForPrune = false;
bool fDoFullFlush = false;
LOCK(cs_LastBlockFile);
if (fPruneMode && (fCheckForPruning || nManualPruneHeight > 0) && !fReindex) {
if (nManualPruneHeight > 0) {
@ -2089,7 +2088,7 @@ bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &
}
}
}
nNow = GetTimeMicros();
int64_t nNow = GetTimeMicros();
// Avoid writing/flushing immediately after startup.
if (nLastWrite == 0) {
nLastWrite = nNow;
@ -2097,9 +2096,6 @@ bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &
if (nLastFlush == 0) {
nLastFlush = nNow;
}
if (nLastSetChain == 0) {
nLastSetChain = nNow;
}
int64_t nMempoolSizeMax = gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
int64_t cacheSize = pcoinsTip->DynamicMemoryUsage();
int64_t nTotalSpace = nCoinCacheUsage + std::max<int64_t>(nMempoolSizeMax - nMempoolUsage, 0);
@ -2156,12 +2152,12 @@ bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &
if (!pcoinsTip->Flush())
return AbortNode(state, "Failed to write to coin database");
nLastFlush = nNow;
full_flush_completed = true;
}
}
if (fDoFullFlush || ((mode == FlushStateMode::ALWAYS || mode == FlushStateMode::PERIODIC) && nNow > nLastSetChain + (int64_t)DATABASE_WRITE_INTERVAL * 1000000)) {
if (full_flush_completed) {
// Update best block in wallet (so we can detect restored wallets).
GetMainSignals().ChainStateFlushed(chainActive.GetLocator());
nLastSetChain = nNow;
}
} catch (const std::runtime_error& e) {
return AbortNode(state, std::string("System error while flushing: ") + e.what());

11
src/validationinterface.h
View file

@ -99,6 +99,17 @@ protected:
/**
* Notifies listeners of the new active block chain on-disk.
*
* Prior to this callback, any updates are not guaranteed to persist on disk
* (ie clients need to handle shutdown/restart safety by being able to
* understand when some updates were lost due to unclean shutdown).
*
* When this callback is invoked, the validation changes done by any prior
* callback are guaranteed to exist on disk and survive a restart, including
* an unclean shutdown.
*
* Provides a locator describing the best chain, which is likely useful for
* storing current state on disk in client DBs.
*
* Called on a background thread.
*/
virtual void ChainStateFlushed(const CBlockLocator &locator) {}