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foundationdb/fdbrpc/AsyncFileCached.actor.h

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/*
* AsyncFileCached.actor.h
*
* This source file is part of the FoundationDB open source project
*
* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
*
* 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.
*/
#pragma once
// When actually compiled (NO_INTELLISENSE), include the generated version of this file. In intellisense use the source version.
#if defined(NO_INTELLISENSE) && !defined(FLOW_ASYNCFILECACHED_ACTOR_G_H)
#define FLOW_ASYNCFILECACHED_ACTOR_G_H
#include "fdbrpc/AsyncFileCached.actor.g.h"
#elif !defined(FLOW_ASYNCFILECACHED_ACTOR_H)
#define FLOW_ASYNCFILECACHED_ACTOR_H
#include <boost/intrusive/list.hpp>
#include "flow/flow.h"
#include "fdbrpc/IAsyncFile.h"
#include "flow/Knobs.h"
#include "flow/TDMetric.actor.h"
#include "flow/network.h"
#include "flow/actorcompiler.h" // This must be the last #include.
namespace bi = boost::intrusive;
struct EvictablePage {
void* data;
int index;
class Reference<struct EvictablePageCache> pageCache;
bi::list_member_hook<> member_hook;
virtual bool evict() = 0; // true if page was evicted, false if it isn't immediately evictable (but will be evicted regardless if possible)
EvictablePage(Reference<EvictablePageCache> pageCache) : data(0), index(-1), pageCache(pageCache) {}
virtual ~EvictablePage();
};
struct EvictablePageCache : ReferenceCounted<EvictablePageCache> {
using List = bi::list< EvictablePage, bi::member_hook< EvictablePage, bi::list_member_hook<>, &EvictablePage::member_hook>>;
enum CacheEvictionType { RANDOM = 0, LRU = 1 };
static CacheEvictionType evictionPolicyStringToEnum(const std::string &policy) {
std::string cep = policy;
std::transform(cep.begin(), cep.end(), cep.begin(), ::tolower);
if (cep != "random" && cep != "lru")
throw invalid_cache_eviction_policy();
if (cep == "random")
return RANDOM;
return LRU;
}
EvictablePageCache() : pageSize(0), maxPages(0), cacheEvictionType(RANDOM) {}
explicit EvictablePageCache(int pageSize, int64_t maxSize) : pageSize(pageSize), maxPages(maxSize / pageSize), cacheEvictionType(evictionPolicyStringToEnum(FLOW_KNOBS->CACHE_EVICTION_POLICY)) {
cacheEvictions.init(LiteralStringRef("EvictablePageCache.CacheEvictions"));
}
void allocate(EvictablePage* page) {
try_evict();
try_evict();
page->data = pageSize == 4096 ? FastAllocator<4096>::allocate() : aligned_alloc(4096,pageSize);
if (RANDOM == cacheEvictionType) {
page->index = pages.size();
pages.push_back(page);
} else {
lruPages.push_back(*page); // new page is considered the most recently used (placed at LRU tail)
}
}
void updateHit(EvictablePage* page) {
if (RANDOM != cacheEvictionType) {
// on a hit, update page's location in the LRU so that it's most recent (tail)
lruPages.erase(List::s_iterator_to(*page));
lruPages.push_back(*page);
}
}
void try_evict() {
if (RANDOM == cacheEvictionType) {
if (pages.size() >= (uint64_t)maxPages && !pages.empty()) {
for (int i = 0; i < FLOW_KNOBS->MAX_EVICT_ATTEMPTS; i++) { // If we don't manage to evict anything, just go ahead and exceed the cache limit
int toEvict = deterministicRandom()->randomInt(0, pages.size());
if (pages[toEvict]->evict()) {
++cacheEvictions;
break;
}
}
}
} else {
// For now, LRU is the only other CACHE_EVICTION option
if (lruPages.size() >= (uint64_t)maxPages) {
int i = 0;
// try the least recently used pages first (starting at head of the LRU list)
for (List::iterator it = lruPages.begin();
it != lruPages.end() && i < FLOW_KNOBS->MAX_EVICT_ATTEMPTS;
++it, ++i) { // If we don't manage to evict anything, just go ahead and exceed the cache limit
if (it->evict()) {
++cacheEvictions;
break;
}
}
}
}
}
std::vector<EvictablePage*> pages;
List lruPages;
int pageSize;
int64_t maxPages;
Int64MetricHandle cacheEvictions;
const CacheEvictionType cacheEvictionType;
};
struct OpenFileInfo : NonCopyable {
IAsyncFile* f;
Future<Reference<IAsyncFile>> opened; // Only valid until the file is fully opened
OpenFileInfo() : f(0) {}
OpenFileInfo(OpenFileInfo && r) BOOST_NOEXCEPT : f(r.f), opened(std::move(r.opened)) { r.f = 0; }
Future<Reference<IAsyncFile>> get() {
if (f) return Reference<IAsyncFile>::addRef(f);
else return opened;
}
};
struct AFCPage;
class AsyncFileCached : public IAsyncFile, public ReferenceCounted<AsyncFileCached> {
friend struct AFCPage;
public:
static Future<Reference<IAsyncFile>> open( std::string filename, int flags, int mode ) {
//TraceEvent("AsyncFileCachedOpen").detail("Filename", filename);
if ( openFiles.find(filename) == openFiles.end() ) {
auto f = open_impl( filename, flags, mode );
if ( f.isReady() && f.isError() )
return f;
if( !f.isReady() )
openFiles[filename].opened = f;
else
return f.get();
}
return openFiles[filename].get();
}
virtual Future<int> read( void* data, int length, int64_t offset ) {
++countFileCacheReads;
++countCacheReads;
if (offset + length > this->length) {
length = int(this->length - offset);
ASSERT(length >= 0);
}
auto f = read_write_impl(this, data, length, offset, false);
if( f.isReady() && !f.isError() ) return length;
++countFileCacheReadsBlocked;
++countCacheReadsBlocked;
return tag(f,length);
}
ACTOR static Future<Void> write_impl( AsyncFileCached *self, void const* data, int length, int64_t offset ) {
// If there is a truncate in progress before the the write position then we must
// wait for it to complete.
if(length + offset > self->currentTruncateSize)
wait(self->currentTruncate);
++self->countFileCacheWrites;
++self->countCacheWrites;
Future<Void> f = read_write_impl(self, const_cast<void*>(data), length, offset, true);
if (!f.isReady()) {
++self->countFileCacheWritesBlocked;
++self->countCacheWritesBlocked;
}
wait(f);
return Void();
}
virtual Future<Void> write( void const* data, int length, int64_t offset ) {
return write_impl(this, data, length, offset);
}
virtual Future<Void> readZeroCopy( void** data, int* length, int64_t offset );
virtual void releaseZeroCopy( void* data, int length, int64_t offset );
// This waits for previously started truncates to finish and then truncates
virtual Future<Void> truncate( int64_t size ) {
return truncate_impl(this, size);
}
// This is the 'real' truncate that does the actual removal of cache blocks and then shortens the file
Future<Void> changeFileSize( int64_t size );
// This wrapper for the actual truncation operation enforces ordering of truncates.
// It maintains currentTruncate and currentTruncateSize so writers can wait behind truncates that would affect them.
ACTOR static Future<Void> truncate_impl(AsyncFileCached *self, int64_t size) {
wait(self->currentTruncate);
self->currentTruncateSize = size;
self->currentTruncate = self->changeFileSize(size);
wait(self->currentTruncate);
return Void();
}
virtual Future<Void> sync() {
return waitAndSync( this, flush() );
}
virtual Future<int64_t> size() {
return length;
}
virtual int64_t debugFD() {
return uncached->debugFD();
}
virtual std::string getFilename() {
return filename;
}
virtual void addref() {
ReferenceCounted<AsyncFileCached>::addref();
//TraceEvent("AsyncFileCachedAddRef").detail("Filename", filename).detail("Refcount", debugGetReferenceCount()).backtrace();
}
virtual void delref() {
if (delref_no_destroy()) {
// If this is ever ThreadSafeReferenceCounted...
// setrefCountUnsafe(0);
auto f = quiesce();
//TraceEvent("AsyncFileCachedDel").detail("Filename", filename)
// .detail("Refcount", debugGetReferenceCount()).detail("CanDie", f.isReady()).backtrace();
if (f.isReady())
delete this;
else
uncancellable( holdWhile( Reference<AsyncFileCached>::addRef( this ), f ) );
}
}
~AsyncFileCached();
private:
static std::map< std::string, OpenFileInfo > openFiles;
std::string filename;
Reference<IAsyncFile> uncached;
int64_t length;
int64_t prevLength;
std::unordered_map<int64_t, AFCPage*> pages;
std::vector<AFCPage*> flushable;
Reference<EvictablePageCache> pageCache;
Future<Void> currentTruncate;
int64_t currentTruncateSize;
// Map of pointers which hold page buffers for pages which have been overwritten
// but at the time of write there were still readZeroCopy holders.
std::unordered_map<void *, int> orphanedPages;
Int64MetricHandle countFileCacheFinds;
Int64MetricHandle countFileCacheReads;
Int64MetricHandle countFileCacheWrites;
Int64MetricHandle countFileCacheReadsBlocked;
Int64MetricHandle countFileCacheWritesBlocked;
Int64MetricHandle countFileCachePageReadsHit;
Int64MetricHandle countFileCachePageReadsMissed;
Int64MetricHandle countFileCachePageReadsMerged;
Int64MetricHandle countFileCacheReadBytes;
Int64MetricHandle countCacheFinds;
Int64MetricHandle countCacheReads;
Int64MetricHandle countCacheWrites;
Int64MetricHandle countCacheReadsBlocked;
Int64MetricHandle countCacheWritesBlocked;
Int64MetricHandle countCachePageReadsHit;
Int64MetricHandle countCachePageReadsMissed;
Int64MetricHandle countCachePageReadsMerged;
Int64MetricHandle countCacheReadBytes;
AsyncFileCached( Reference<IAsyncFile> uncached, const std::string& filename, int64_t length, Reference<EvictablePageCache> pageCache )
: uncached(uncached), filename(filename), length(length), prevLength(length), pageCache(pageCache), currentTruncate(Void()), currentTruncateSize(0) {
if( !g_network->isSimulated() ) {
countFileCacheWrites.init(LiteralStringRef("AsyncFile.CountFileCacheWrites"), filename);
countFileCacheReads.init(LiteralStringRef("AsyncFile.CountFileCacheReads"), filename);
countFileCacheWritesBlocked.init(LiteralStringRef("AsyncFile.CountFileCacheWritesBlocked"), filename);
countFileCacheReadsBlocked.init(LiteralStringRef("AsyncFile.CountFileCacheReadsBlocked"), filename);
countFileCachePageReadsHit.init(LiteralStringRef("AsyncFile.CountFileCachePageReadsHit"), filename);
countFileCachePageReadsMissed.init(LiteralStringRef("AsyncFile.CountFileCachePageReadsMissed"), filename);
countFileCachePageReadsMerged.init(LiteralStringRef("AsyncFile.CountFileCachePageReadsMerged"), filename);
countFileCacheFinds.init(LiteralStringRef("AsyncFile.CountFileCacheFinds"), filename);
countFileCacheReadBytes.init(LiteralStringRef("AsyncFile.CountFileCacheReadBytes"), filename);
countCacheWrites.init(LiteralStringRef("AsyncFile.CountCacheWrites"));
countCacheReads.init(LiteralStringRef("AsyncFile.CountCacheReads"));
countCacheWritesBlocked.init(LiteralStringRef("AsyncFile.CountCacheWritesBlocked"));
countCacheReadsBlocked.init(LiteralStringRef("AsyncFile.CountCacheReadsBlocked"));
countCachePageReadsHit.init(LiteralStringRef("AsyncFile.CountCachePageReadsHit"));
countCachePageReadsMissed.init(LiteralStringRef("AsyncFile.CountCachePageReadsMissed"));
countCachePageReadsMerged.init(LiteralStringRef("AsyncFile.CountCachePageReadsMerged"));
countCacheFinds.init(LiteralStringRef("AsyncFile.CountCacheFinds"));
countCacheReadBytes.init(LiteralStringRef("AsyncFile.CountCacheReadBytes"));
}
}
static Future<Reference<IAsyncFile>> open_impl( std::string filename, int flags, int mode );
ACTOR static Future<Reference<IAsyncFile>> open_impl( std::string filename, int flags, int mode, Reference<EvictablePageCache> pageCache ) {
try {
TraceEvent("AFCUnderlyingOpenBegin").detail("Filename", filename);
if(flags & IAsyncFile::OPEN_CACHED_READ_ONLY)
flags = (flags & ~IAsyncFile::OPEN_READWRITE) | IAsyncFile::OPEN_READONLY;
else
flags = (flags & ~IAsyncFile::OPEN_READONLY) | IAsyncFile::OPEN_READWRITE;
state Reference<IAsyncFile> f = wait( IAsyncFileSystem::filesystem()->open(filename, flags | IAsyncFile::OPEN_UNCACHED | IAsyncFile::OPEN_UNBUFFERED, mode) );
TraceEvent("AFCUnderlyingOpenEnd").detail("Filename", filename);
int64_t l = wait( f->size() );
TraceEvent("AFCUnderlyingSize").detail("Filename", filename).detail("Size", l);
auto& of = openFiles[filename];
of.f = new AsyncFileCached(f, filename, l, pageCache);
of.opened = Future<Reference<IAsyncFile>>();
return Reference<IAsyncFile>( of.f );
} catch (Error& e) {
if( e.code() != error_code_actor_cancelled )
openFiles.erase( filename );
throw e;
}
}
virtual Future<Void> flush();
Future<Void> quiesce();
ACTOR static Future<Void> waitAndSync( AsyncFileCached* self, Future<Void> flush ) {
wait( flush );
wait( self->uncached->sync() );
return Void();
}
static Future<Void> read_write_impl( AsyncFileCached* self, void* data, int length, int64_t offset, bool writing );
void remove_page( AFCPage* page );
};
struct AFCPage : public EvictablePage, public FastAllocated<AFCPage> {
virtual bool evict() {
if ( notReading.isReady() && notFlushing.isReady() && !dirty && !zeroCopyRefCount && !truncated ) {
owner->remove_page( this );
delete this;
return true;
}
if (dirty)
flush();
return false;
}
// Move this page's data into the orphanedPages set of the owner
void orphan() {
owner->orphanedPages[data] = zeroCopyRefCount;
zeroCopyRefCount = 0;
notReading = Void();
data = pageCache->pageSize == 4096 ? FastAllocator<4096>::allocate() : aligned_alloc(4096, pageCache->pageSize);
}
Future<Void> write( void const* data, int length, int offset ) {
// If zero-copy reads are in progress, allow whole page writes to a new page buffer so the effects
// are not seen by the prior readers who still hold zeroCopyRead pointers
bool fullPage = offset == 0 && length == pageCache->pageSize;
ASSERT(zeroCopyRefCount == 0 || fullPage);
if(zeroCopyRefCount != 0) {
ASSERT(fullPage);
orphan();
}
setDirty();
// If there are no active readers then if data is valid or we're replacing all of it we can write directly
if (valid || fullPage) {
if(!fullPage) {
++owner->countFileCachePageReadsHit;
++owner->countCachePageReadsHit;
}
valid = true;
memcpy( static_cast<uint8_t*>(this->data) + offset, data, length );
return yield();
}
++owner->countFileCachePageReadsMissed;
++owner->countCachePageReadsMissed;
// If data is not valid but no read is in progress, start reading
if (notReading.isReady()) {
notReading = readThrough( this );
}
notReading = waitAndWrite( this, data, length, offset );
return notReading;
}
ACTOR static Future<Void> waitAndWrite( AFCPage* self, void const* data, int length, int offset ) {
wait( self->notReading );
memcpy( static_cast<uint8_t*>(self->data) + offset, data, length );
return Void();
}
Future<Void> readZeroCopy() {
++zeroCopyRefCount;
if (valid) {
++owner->countFileCachePageReadsHit;
++owner->countCachePageReadsHit;
return yield();
}
++owner->countFileCachePageReadsMissed;
++owner->countCachePageReadsMissed;
if (notReading.isReady()) {
notReading = readThrough( this );
} else {
++owner->countFileCachePageReadsMerged;
++owner->countCachePageReadsMerged;
}
return notReading;
}
void releaseZeroCopy() {
--zeroCopyRefCount;
ASSERT( zeroCopyRefCount >= 0 );
}
Future<Void> read( void* data, int length, int offset ) {
if (valid) {
++owner->countFileCachePageReadsHit;
++owner->countCachePageReadsHit;
owner->countFileCacheReadBytes += length;
owner->countCacheReadBytes += length;
memcpy( data, static_cast<uint8_t const*>(this->data) + offset, length );
return yield();
}
++owner->countFileCachePageReadsMissed;
++owner->countCachePageReadsMissed;
if (notReading.isReady()) {
notReading = readThrough( this );
} else {
++owner->countFileCachePageReadsMerged;
++owner->countCachePageReadsMerged;
}
notReading = waitAndRead( this, data, length, offset );
return notReading;
}
ACTOR static Future<Void> waitAndRead( AFCPage* self, void* data, int length, int offset ) {
wait( self->notReading );
memcpy( data, static_cast<uint8_t const*>(self->data) + offset, length );
return Void();
}
ACTOR static Future<Void> readThrough( AFCPage* self ) {
ASSERT(!self->valid);
state void *dst = self->data;
if ( self->pageOffset < self->owner->prevLength ) {
try {
int _ = wait( self->owner->uncached->read( dst, self->pageCache->pageSize, self->pageOffset ) );
if (_ != self->pageCache->pageSize)
TraceEvent("ReadThroughShortRead").detail("ReadAmount", _).detail("PageSize", self->pageCache->pageSize).detail("PageOffset", self->pageOffset);
} catch (Error& e) {
self->zeroCopyRefCount = 0;
TraceEvent("ReadThroughFailed").error(e);
throw;
}
}
// If the memory we read into wasn't orphaned while we were waiting on the read then set valid to true
if(dst == self->data)
self->valid = true;
return Void();
}
ACTOR static Future<Void> writeThrough( AFCPage* self, Promise<Void> writing ) {
// writeThrough can be called on a page that is not dirty, just to wait for a previous writeThrough to finish. In that
// case we don't want to do any disk I/O
try {
state bool dirty = self->dirty;
++self->writeThroughCount;
self->updateFlushableIndex();
wait( self->notReading && self->notFlushing );
if (dirty) {
if ( self->pageOffset + self->pageCache->pageSize > self->owner->length ) {
ASSERT(self->pageOffset < self->owner->length);
memset( static_cast<uint8_t *>(self->data) + self->owner->length - self->pageOffset, 0, self->pageCache->pageSize - (self->owner->length - self->pageOffset) );
}
auto f = self->owner->uncached->write( self->data, self->pageCache->pageSize, self->pageOffset );
wait( f );
}
}
catch(Error& e) {
--self->writeThroughCount;
self->setDirty();
writing.sendError(e);
throw;
}
--self->writeThroughCount;
self->updateFlushableIndex();
writing.send(Void()); // FIXME: This could happen before the wait if AsyncFileKAIO dealt properly with overlapping write and sync operations
self->pageCache->try_evict();
return Void();
}
Future<Void> flush() {
if (!dirty && notFlushing.isReady()) return Void();
ASSERT(valid || !notReading.isReady() || notReading.isError());
Promise<Void> writing;
notFlushing = writeThrough( this, writing );
clearDirty(); // Do this last so that if writeThrough immediately calls try_evict, we can't be evicted before assigning notFlushing
return writing.getFuture();
}
Future<Void> quiesce() {
if (dirty) flush();
// If we are flushing, we will be quiescent when all flushes are finished
// Returning flush() isn't right, because flush can return before notFlushing.isReady()
if (!notFlushing.isReady()) {
return notFlushing;
}
// else if we are reading, we will be quiescent when the read is finished
if ( !notReading.isReady() )
return notReading;
return Void();
}
Future<Void> truncate() {
// Allow truncatation during zero copy reads but orphan the previous buffer
if( zeroCopyRefCount != 0)
orphan();
truncated = true;
return truncate_impl( this );
}
ACTOR static Future<Void> truncate_impl( AFCPage* self ) {
wait( self->notReading && self->notFlushing && yield() );
delete self;
return Void();
}
AFCPage( AsyncFileCached* owner, int64_t offset ) : EvictablePage(owner->pageCache), owner(owner), pageOffset(offset), dirty(false), valid(false), truncated(false), notReading(Void()), notFlushing(Void()), zeroCopyRefCount(0), flushableIndex(-1), writeThroughCount(0) {
pageCache->allocate(this);
}
virtual ~AFCPage() {
clearDirty();
ASSERT_ABORT( flushableIndex == -1 );
}
void setDirty() {
dirty = true;
updateFlushableIndex();
}
void clearDirty() {
dirty = false;
updateFlushableIndex();
}
void updateFlushableIndex() {
bool flushable = dirty || writeThroughCount;
if (flushable == (flushableIndex != -1)) return;
if (flushable) {
flushableIndex = owner->flushable.size();
owner->flushable.push_back(this);
} else {
ASSERT( owner->flushable[flushableIndex] == this );
owner->flushable[flushableIndex] = owner->flushable.back();
owner->flushable[flushableIndex]->flushableIndex = flushableIndex;
owner->flushable.pop_back();
flushableIndex = -1;
}
}
AsyncFileCached* owner;
int64_t pageOffset;
Future<Void> notReading; // .isReady when a readThrough (or waitAndWrite) is not in progress
Future<Void> notFlushing; // .isReady when a writeThrough is not in progress
bool dirty; // write has been called more recently than flush
bool valid; // data contains the file contents
bool truncated; // true if this page has been truncated
int writeThroughCount; // number of writeThrough actors that are in progress (potentially writing or waiting to write)
int flushableIndex; // index in owner->flushable[]
int zeroCopyRefCount; // references held by "zero-copy" reads
};
#include "flow/unactorcompiler.h"
#endif
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