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-rw-r--r--cpp/include/IceUtil/Cache.h362
1 files changed, 0 insertions, 362 deletions
diff --git a/cpp/include/IceUtil/Cache.h b/cpp/include/IceUtil/Cache.h
deleted file mode 100644
index cb76f4466e0..00000000000
--- a/cpp/include/IceUtil/Cache.h
+++ /dev/null
@@ -1,362 +0,0 @@
-// **********************************************************************
-//
-// Copyright (c) 2003-2015 ZeroC, Inc. All rights reserved.
-//
-// This copy of Ice is licensed to you under the terms described in the
-// ICE_LICENSE file included in this distribution.
-//
-// **********************************************************************
-
-#ifndef ICE_UTIL_CACHE_H
-#define ICE_UTIL_CACHE_H
-
-#include <IceUtil/Handle.h>
-#include <IceUtil/Mutex.h>
-#include <IceUtil/CountDownLatch.h>
-#include <map>
-
-namespace IceUtil
-{
-
-//
-// An abstraction to efficiently populate a Cache, without holding
-// a lock while loading from a database.
-//
-
-template<typename Key, typename Value>
-class Cache
-{
-public:
-
- //
- // Latch and CacheValue are implementation details;
- // application code should not use them.
- //
-
- struct Latch : public IceUtilInternal::CountDownLatch
- {
- Latch() :
- IceUtilInternal::CountDownLatch(1),
- useCount(0)
- {
- }
- int useCount;
- };
-
- struct CacheValue
- {
- CacheValue(const Handle<Value>& o) :
- obj(o),
- latch(0)
- {
- }
-
- Handle<Value> obj;
- Latch* latch;
- };
-
- typedef typename std::map<Key, CacheValue>::iterator Position;
-
- Handle<Value> getIfPinned(const Key&, bool = false) const;
-
- void unpin(Position);
-
- void clear();
- size_t size() const;
-
- bool pin(const Key&, const Handle<Value>&);
-
- Handle<Value> pin(const Key&);
- Handle<Value> putIfAbsent(const Key&, const Handle<Value>&);
-
-protected:
-
- virtual Handle<Value> load(const Key&) = 0;
-
- virtual void pinned(const Handle<Value>&, Position)
- {
- }
-
- virtual ~Cache()
- {
- }
-
-private:
-
- Handle<Value> pinImpl(const Key&, const Handle<Value>&);
-
- typedef std::map<Key, CacheValue> CacheMap;
-
- Mutex _mutex;
- CacheMap _map;
-};
-
-
-template<typename Key, typename Value> Handle<Value>
-Cache<Key, Value>::getIfPinned(const Key& key, bool wait) const
-{
- Mutex::Lock sync(_mutex);
-
- for(;;)
- {
- typename CacheMap::const_iterator p = _map.find(key);
- if(p != _map.end())
- {
- Handle<Value> result = (*p).second.obj;
- if(result != 0 || wait == false)
- {
- return result;
- }
-
- //
- // The object is being loaded: we wait
- //
-
- if(p->second.latch == 0)
- {
- const_cast<CacheValue&>(p->second).latch = new Latch;
- }
-
- Latch* latch = p->second.latch;
- ++latch->useCount;
- sync.release();
- latch->await();
- sync.acquire();
- if(--latch->useCount == 0)
- {
- delete latch;
- }
- //
- // Try again
- //
- }
- else
- {
- return 0;
- }
- }
-}
-
-template<typename Key, typename Value> void
-Cache<Key, Value>::unpin(typename Cache::Position p)
-{
- //
- // There is no risk to erase a 'being loaded' position,
- // since such position never got outside yet!
- //
- Mutex::Lock sync(_mutex);
- _map.erase(p);
-}
-
-template<typename Key, typename Value> void
-Cache<Key, Value>::clear()
-{
- //
- // Not safe during a pin!
- //
- Mutex::Lock sync(_mutex);
- _map.clear();
-}
-
-template<typename Key, typename Value> size_t
-Cache<Key, Value>::size() const
-{
- Mutex::Lock sync(_mutex);
- return _map.size();
-}
-
-template<typename Key, typename Value> bool
-Cache<Key, Value>::pin(const Key& key, const Handle<Value>& obj)
-{
- Mutex::Lock sync(_mutex);
- std::pair<typename CacheMap::iterator, bool> ir =
-#ifdef _MSC_VER
- _map.insert(CacheMap::value_type(key, CacheValue(obj)));
-#else
- _map.insert(typename CacheMap::value_type(key, CacheValue(obj)));
-#endif
-
- if(ir.second)
- {
- pinned(obj, ir.first);
- }
- return ir.second;
-}
-
-template<typename Key, typename Value> Handle<Value>
-Cache<Key, Value>::pin(const Key& key)
-{
- return pinImpl(key, 0);
-}
-
-template<typename Key, typename Value> Handle<Value>
-Cache<Key, Value>::putIfAbsent(const Key& key, const Handle<Value>& obj)
-{
- return pinImpl(key, obj);
-}
-
-template<typename Key, typename Value> Handle<Value>
-Cache<Key, Value>::pinImpl(const Key& key, const Handle<Value>& newObj)
-{
- Latch* latch = 0;
- Position p;
-
- do
- {
- {
- Mutex::Lock sync(_mutex);
-
- //
- // Clean up latch from previous loop
- //
- if(latch != 0)
- {
- if(--latch->useCount == 0)
- {
- delete latch;
- }
- latch = 0;
- }
-
- std::pair<typename CacheMap::iterator, bool> ir =
-#if defined(_MSC_VER)
- _map.insert(CacheMap::value_type(key, CacheValue(0)));
-#else
- _map.insert(typename CacheMap::value_type(key, CacheValue(0)));
-#endif
-
- if(ir.second == false)
- {
- CacheValue& val = ir.first->second;
- if(val.obj != 0)
- {
- return val.obj;
- }
-
- //
- // Otherwise wait
- //
- if(val.latch == 0)
- {
- //
- // The first queued thread creates the latch
- //
- val.latch = new Latch;
- }
- latch = val.latch;
- latch->useCount++;
- }
-
- p = ir.first;
- }
-
- if(latch != 0)
- {
- //
- // Note: only the threads owning a "useCount" wait; upon wake-up,
- // they loop back, release this useCount and possibly delete the latch
- //
-
- latch->await();
-
- //
- // p could be stale now, e.g. some other thread pinned and unpinned the
- // object while we were waiting.
- // So start over.
- }
- } while(latch != 0);
-
-
- //
- // Load
- //
- Handle<Value> obj;
- try
- {
- obj = load(key);
- }
- catch(...)
- {
- Mutex::Lock sync(_mutex);
- latch = p->second.latch;
- p->second.latch = 0;
- _map.erase(p);
- if(latch != 0)
- {
- //
- // It is necessary to call countDown() within the sync
- // because countDown may not be atomic, and we don't
- // want the "await" thread to delete the latch while
- // this thread is still in countDown().
- //
- assert(latch->getCount() == 1);
- latch->countDown();
- }
- throw;
- }
-
- Mutex::Lock sync(_mutex);
-
- //
- // p is still valid here -- nobody knows about it. See also unpin().
- //
- latch = p->second.latch;
- p->second.latch = 0;
-
- try
- {
- if(obj != 0)
- {
- p->second.obj = obj;
- pinned(obj, p);
- }
- else
- {
- if(newObj == 0)
- {
- //
- // pin() did not find the object
- //
-
- //
- // The waiting threads will have to call load() to see by themselves.
- //
- _map.erase(p);
- }
- else
- {
- //
- // putIfAbsent() inserts key/newObj
- //
- p->second.obj = newObj;
- pinned(newObj, p);
- }
- }
- }
- catch(...)
- {
- if(latch != 0)
- {
- //
- // Must be called within sync; see ->countDown() note above.
- //
- assert(latch->getCount() == 1);
- latch->countDown();
- }
- throw;
- }
-
- if(latch != 0)
- {
- //
- // Must be called within sync; see ->countDown() note above.
- //
- assert(latch->getCount() == 1);
- latch->countDown();
- }
- return obj;
-}
-
-}
-
-#endif
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