TURF_TRACE_DECLARE(LeapFrog, 33)
-template<class Map>
+template <class Map>
struct LeapFrog {
typedef typename Map::Hash Hash;
typedef typename Map::Value Value;
static const ureg TableMigrationUnitSize = 32;
static const ureg LinearSearchLimit = 128;
static const ureg CellsInUseSample = LinearSearchLimit;
- TURF_STATIC_ASSERT(LinearSearchLimit > 0 && LinearSearchLimit < 256); // Must fit in CellGroup::links
+ TURF_STATIC_ASSERT(LinearSearchLimit > 0 && LinearSearchLimit < 256); // Must fit in CellGroup::links
TURF_STATIC_ASSERT(CellsInUseSample > 0 && CellsInUseSample <= LinearSearchLimit); // Limit sample to failed search chain
struct Cell {
};
struct Table {
- const ureg sizeMask; // a power of two minus one
- turf::Mutex mutex; // to DCLI the TableMigration (stored in the jobCoordinator)
- SimpleJobCoordinator jobCoordinator; // makes all blocked threads participate in the migration
+ const ureg sizeMask; // a power of two minus one
+ turf::Mutex mutex; // to DCLI the TableMigration (stored in the jobCoordinator)
+ SimpleJobCoordinator jobCoordinator; // makes all blocked threads participate in the migration
Table(ureg sizeMask) : sizeMask(sizeMask) {
}
TURF_ASSERT(tableSize >= 4);
ureg numGroups = tableSize >> 2;
Table* table = (Table*) TURF_HEAP.alloc(sizeof(Table) + sizeof(CellGroup) * numGroups);
- new(table) Table(tableSize - 1);
+ new (table) Table(tableSize - 1);
for (ureg i = 0; i < numGroups; i++) {
CellGroup* group = table->getCellGroups() + i;
for (ureg j = 0; j < 4; j++) {
Map& m_map;
Table* m_destination;
- turf::Atomic<ureg> m_workerStatus; // number of workers + end flag
+ turf::Atomic<ureg> m_workerStatus; // number of workers + end flag
turf::Atomic<bool> m_overflowed;
turf::Atomic<sreg> m_unitsRemaining;
ureg m_numSources;
}
static TableMigration* create(Map& map, ureg numSources) {
- TableMigration* migration = (TableMigration*) TURF_HEAP.alloc(sizeof(TableMigration) + sizeof(TableMigration::Source) * numSources);
- new(migration) TableMigration(map);
+ TableMigration* migration =
+ (TableMigration*) TURF_HEAP.alloc(sizeof(TableMigration) + sizeof(TableMigration::Source) * numSources);
+ new (migration) TableMigration(map);
migration->m_workerStatus.storeNonatomic(0);
migration->m_overflowed.storeNonatomic(false);
migration->m_unitsRemaining.storeNonatomic(0);
}
// FIXME: Possible optimization: Dedicated insert for migration? It wouldn't check for InsertResult_AlreadyFound.
- enum InsertResult {
- InsertResult_AlreadyFound,
- InsertResult_InsertedNew,
- InsertResult_Overflow
- };
+ enum InsertResult { InsertResult_AlreadyFound, InsertResult_InsertedNew, InsertResult_Overflow };
static InsertResult insert(Hash hash, Table* table, Cell*& cell, ureg& overflowIdx) {
TURF_TRACE(LeapFrog, 3, "[insert] called", uptr(table), hash);
TURF_ASSERT(table);
probeHash = cell->hash.load(turf::Acquire);
} while (probeHash == KeyTraits::NullHash);
}
- TURF_ASSERT(((probeHash ^ hash) & sizeMask) == 0); // Only hashes in same bucket can be linked
+ TURF_ASSERT(((probeHash ^ hash) & sizeMask) == 0); // Only hashes in same bucket can be linked
if (probeHash == hash) {
TURF_TRACE(LeapFrog, 8, "[insert] found in probe chain", uptr(table), idx);
return InsertResult_AlreadyFound;
// Reached the end of the link chain for this bucket.
// Switch to linear probing until we reserve a new cell or find a late-arriving cell in the same bucket.
ureg prevLinkIdx = idx;
- TURF_ASSERT(sreg(maxIdx - idx) >= 0); // Nobody would have linked an idx that's out of range.
+ TURF_ASSERT(sreg(maxIdx - idx) >= 0); // Nobody would have linked an idx that's out of range.
ureg linearProbesRemaining = turf::util::min(maxIdx - idx, LinearSearchLimit);
while (linearProbesRemaining-- > 0) {
idx++;
TURF_TRACE(LeapFrog, 9, "[insert] reserved cell", uptr(table), idx);
TURF_ASSERT(probeDelta == 0);
u8 desiredDelta = idx - prevLinkIdx;
-#if TURF_WITH_ASSERTS
+#if TURF_WITH_ASSERTS
probeDelta = prevLink->exchange(desiredDelta, turf::Relaxed);
TURF_ASSERT(probeDelta == 0 || probeDelta == desiredDelta);
#else
// there's no guarantee that our own link chain will be well-formed by the time this function returns.
// (Indeed, subsequent lookups sometimes failed during testing, for this exact reason.)
u8 desiredDelta = idx - prevLinkIdx;
-#if TURF_WITH_ASSERTS
+#if TURF_WITH_ASSERTS
probeDelta = prevLink->exchange(desiredDelta, turf::Relaxed);
TURF_ASSERT(probeDelta == 0 || probeDelta == desiredDelta);
if (probeDelta == 0)
TURF_TRACE(LeapFrog, 13, "[insert] set link on behalf of late-arriving cell", uptr(table), idx);
#else
prevLink->store(desiredDelta, turf::Relaxed);
-#endif
- goto followLink; // Try to follow link chain for the bucket again.
+#endif
+ goto followLink; // Try to follow link chain for the bucket again.
}
// Continue linear search...
}
TURF_TRACE(LeapFrog, 16, "[beginTableMigrationToSize] new migration already exists", 0, 0);
} else {
turf::LockGuard<turf::Mutex> guard(table->mutex);
- job = table->jobCoordinator.loadConsume(); // Non-atomic would be sufficient, but that's OK.
+ job = table->jobCoordinator.loadConsume(); // Non-atomic would be sufficient, but that's OK.
if (job) {
TURF_TRACE(LeapFrog, 17, "[beginTableMigrationToSize] new migration already exists (double-checked)", 0, 0);
} else {
}
}; // LeapFrog
-template<class Map>
+template <class Map>
bool LeapFrog<Map>::TableMigration::migrateRange(Table* srcTable, ureg startIdx) {
ureg srcSizeMask = srcTable->sizeMask;
ureg endIdx = turf::util::min(startIdx + TableMigrationUnitSize, srcSizeMask + 1);
srcHash = srcCell->hash.load(turf::Relaxed);
if (srcHash == KeyTraits::NullHash) {
// An unused cell. Try to put a Redirect marker in its value.
- srcValue = srcCell->value.compareExchange(Value(ValueTraits::NullValue), Value(ValueTraits::Redirect), turf::Relaxed);
+ srcValue =
+ srcCell->value.compareExchange(Value(ValueTraits::NullValue), Value(ValueTraits::Redirect), turf::Relaxed);
if (srcValue == Value(ValueTraits::Redirect)) {
// srcValue is already marked Redirect due to previous incomplete migration.
TURF_TRACE(LeapFrog, 19, "[migrateRange] empty cell already redirected", uptr(srcTable), srcIdx);
break;
}
if (srcValue == Value(ValueTraits::NullValue))
- break; // Redirect has been placed. Break inner loop, continue outer loop.
+ break; // Redirect has been placed. Break inner loop, continue outer loop.
TURF_TRACE(LeapFrog, 20, "[migrateRange] race to insert key", uptr(srcTable), srcIdx);
// Otherwise, somebody just claimed the cell. Read srcHash again...
} else {
if (srcValue == Value(ValueTraits::NullValue)) {
// Try to put a Redirect marker.
if (srcCell->value.compareExchangeStrong(srcValue, Value(ValueTraits::Redirect), turf::Relaxed))
- break; // Redirect has been placed. Break inner loop, continue outer loop.
+ break; // Redirect has been placed. Break inner loop, continue outer loop.
TURF_TRACE(LeapFrog, 21, "[migrateRange] race to insert value", uptr(srcTable), srcIdx);
if (srcValue == Value(ValueTraits::Redirect)) {
// FIXME: I don't think this will happen. Investigate & change to assert
TURF_TRACE(LeapFrog, 23, "[migrateRange] in-use cell already redirected", uptr(srcTable), srcIdx);
break;
}
-
+
// We've got a key/value pair to migrate.
// Reserve a destination cell in the destination.
TURF_ASSERT(srcHash != KeyTraits::NullHash);
// Copy srcValue to the destination.
dstCell->value.store(srcValue, turf::Relaxed);
// Try to place a Redirect marker in srcValue.
- Value doubleCheckedSrcValue = srcCell->value.compareExchange(srcValue, Value(ValueTraits::Redirect), turf::Relaxed);
- TURF_ASSERT(doubleCheckedSrcValue != Value(ValueTraits::Redirect)); // Only one thread can redirect a cell at a time.
+ Value doubleCheckedSrcValue =
+ srcCell->value.compareExchange(srcValue, Value(ValueTraits::Redirect), turf::Relaxed);
+ TURF_ASSERT(doubleCheckedSrcValue !=
+ Value(ValueTraits::Redirect)); // Only one thread can redirect a cell at a time.
if (doubleCheckedSrcValue == srcValue) {
// No racing writes to the src. We've successfully placed the Redirect marker.
// srcValue was non-NULL when we decided to migrate it, but it may have changed to NULL
}
ureg startIdx = source.sourceIndex.fetchAdd(TableMigrationUnitSize, turf::Relaxed);
if (startIdx >= source.table->sizeMask + 1)
- break; // No more migration units in this table. Try next source table.
+ break; // No more migration units in this table. Try next source table.
bool overflowed = !migrateRange(source.table, startIdx);
if (overflowed) {
// *** FAILED MIGRATION ***
// TableMigration failed due to destination table overflow.
- // No other thread can declare the migration successful at this point, because *this* unit will never complete, hence m_unitsRemaining won't reach zero.
+ // No other thread can declare the migration successful at this point, because *this* unit will never complete,
+ // hence m_unitsRemaining won't reach zero.
// However, multiple threads can independently detect a failed migration at the same time.
TURF_TRACE(LeapFrog, 28, "[TableMigration::run] destination overflow", uptr(source.table), uptr(startIdx));
// The reason we store overflowed in a shared variable is because we can must flush all the worker threads before
- // we can safely deal with the overflow. Therefore, the thread that detects the failure is often different from the thread
+ // we can safely deal with the overflow. Therefore, the thread that detects the failure is often different from
+ // the thread
// that deals with it.
bool oldOverflowed = m_overflowed.exchange(overflowed, turf::Relaxed);
if (oldOverflowed)
- TURF_TRACE(LeapFrog, 29, "[TableMigration::run] race to set m_overflowed", uptr(overflowed), uptr(oldOverflowed));
+ TURF_TRACE(LeapFrog, 29, "[TableMigration::run] race to set m_overflowed", uptr(overflowed),
+ uptr(oldOverflowed));
m_workerStatus.fetchOr(1, turf::Relaxed);
goto endMigration;
}
endMigration:
// Decrement the shared # of workers.
- probeStatus = m_workerStatus.fetchSub(2, turf::AcquireRelease); // AcquireRelease makes all previous writes visible to the last worker thread.
+ probeStatus = m_workerStatus.fetchSub(
+ 2, turf::AcquireRelease); // AcquireRelease makes all previous writes visible to the last worker thread.
if (probeStatus >= 4) {
// There are other workers remaining. Return here so that only the very last worker will proceed.
TURF_TRACE(LeapFrog, 31, "[TableMigration::run] not the last worker", uptr(this), uptr(probeStatus));
// We're the very last worker thread.
// Perform the appropriate post-migration step depending on whether the migration succeeded or failed.
TURF_ASSERT(probeStatus == 3);
- bool overflowed = m_overflowed.loadNonatomic(); // No racing writes at this point
+ bool overflowed = m_overflowed.loadNonatomic(); // No racing writes at this point
if (!overflowed) {
// The migration succeeded. This is the most likely outcome. Publish the new subtree.
m_map.publishTableMigration(this);
turf::LockGuard<turf::Mutex> guard(origTable->mutex);
SimpleJobCoordinator::Job* checkedJob = origTable->jobCoordinator.loadConsume();
if (checkedJob != this) {
- TURF_TRACE(LeapFrog, 32, "[TableMigration::run] a new TableMigration was already started", uptr(origTable), uptr(checkedJob));
+ TURF_TRACE(LeapFrog, 32, "[TableMigration::run] a new TableMigration was already started", uptr(origTable),
+ uptr(checkedJob));
} else {
TableMigration* migration = TableMigration::create(m_map, m_numSources + 1);
// Double the destination table size.
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