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Page Speed Optimization Libraries
1.13.35.1
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Page Speed Optimization Libraries
1.13.35.1
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#include "async_cache.h"
Public Member Functions | |
| AsyncCache (CacheInterface *cache, QueuedWorkerPool *pool) | |
| virtual void | Get (const GoogleString &key, Callback *callback) |
| virtual void | Put (const GoogleString &key, const SharedString &value) |
| virtual void | Delete (const GoogleString &key) |
| virtual void | MultiGet (MultiGetRequest *request) |
| virtual GoogleString | Name () const |
| virtual bool | IsBlocking () const |
| virtual void | ShutDown () |
| void | CancelPendingOperations () |
| virtual bool | IsHealthy () const |
| int32 | outstanding_operations () |
 Public Member Functions inherited from net_instaweb::CacheInterface | |
| void | PutSwappingString (const GoogleString &key, GoogleString *value) |
| virtual CacheInterface * | Backend () |
| virtual bool | MustEncodeKeyInValueOnPut () const |
| virtual void | PutWithKeyInValue (const GoogleString &key, const SharedString &key_and_value) |
Static Public Member Functions | |
| static GoogleString | FormatName (StringPiece cache) |
| Static Public Member Functions inherited from net_instaweb::CacheInterface | |
| static const char * | KeyStateName (KeyState state) |
Static Public Attributes | |
| static const int64 | kMaxQueueSize = 2000 |
Additional Inherited Members | |
| Public Types inherited from net_instaweb::CacheInterface | |
| enum | KeyState { kAvailable = 0, kNotFound = 1, kOverload = 2, kNetworkError = 3, kTimeout = 4 } |
| typedef std::vector< KeyCallback > | MultiGetRequest |
| Protected Member Functions inherited from net_instaweb::CacheInterface | |
| void | ValidateAndReportResult (const GoogleString &key, KeyState state, Callback *callback) |
| Invokes callback->ValidateCandidate() and callback->Done() as appropriate. | |
| void | ReportMultiGetNotFound (MultiGetRequest *request) |
Employs a QueuedWorkerPool to turn a synchronous cache implementation into an asynchronous one. This makes sense to do only if the cache implemention is potentially slow, due to network latency or disk seek time.
This class also serves to serialize access to the passed-in cache, ensuring that it is accessed from only one thread at a time.
| net_instaweb::AsyncCache::AsyncCache | ( | CacheInterface * | cache, |
| QueuedWorkerPool * | pool | ||
| ) |
Does not takes ownership of the synchronous cache that is passed in. Does not take ownership of the pool, which might be shared with other users.
Note that in the future we may try to add multi-threaded access to the underlying cache (e.g. AprMemCache supports this), so we take the pool as the constructor arg.
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inline |
Cancels all pending cache operations. Puts and Deletes are dropped. Gets and MultiGets are retired by calling their callbacks with kNotFound.
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virtual |
Initiates a cache fetch, calling callback->ValidateCandidate() and then callback->Done(state) when done.
Note: implementations should normally invoke the callback via ValidateAndReportResult, which will combine ValidateCandidate() and Done() together properly.
Implements net_instaweb::CacheInterface.
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inlinevirtual |
Returns true if this cache is guaranteed to call its callbacks before returning from Get and MultiGet.
Implements net_instaweb::CacheInterface.
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inlinevirtual |
IsHealthy() is a rough estimation of whether cache is available for any operations. If it's false, caller may reasonably expect that making calls right now is useless as they will fail or have high latency. If it's true, operations should succeed, but some still may fail occasionally. The primary goal is to avoid sending commands to 'unhealthy' caches, e.g. if cache is under heavy load, we do not want to send even more requests.
Memory and file-based caches can simply return 'true'. It should be safe to call this frequently – the implementation shouldn't do much more that check a bool flag under mutex.
Implements net_instaweb::CacheInterface.
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virtual |
Gets multiple keys, calling multiple callbacks. Default implementation simply loops over all the keys and calls Get.
MultiGetRequest, declared above, is a vector of structs of keys and callbacks.
Ownership of the request is transferred to this function.
Reimplemented from net_instaweb::CacheInterface.
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inlinevirtual |
The name of this CacheInterface – used for logging and debugging.
It is strongly recommended that you provide a static GoogleString FormatName(...) method for use in formatting the Name() return, and in testing, e.g. in third_party/pagespeed/system/system_caches_test.cc.
Implements net_instaweb::CacheInterface.
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virtual |
Puts a value into the cache. The value that is passed in is not modified, but the SharedString is passed by non-const pointer because its reference count is bumped.
Implements net_instaweb::CacheInterface.
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virtual |
Prevent the AsyncCache from issuing any more Gets. Any subsequent Gets will have their callback invoked immediately with kNotFound. Outstanding Gets may be completed depending on timing.
This can be called during the process Shutdown flow to avoid introducing more work asynchronously that will have to be completed prior to Shutdown.
Implements net_instaweb::CacheInterface.
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static |
The maximum number of operations that can be queued up while a server is slow. When this is reached, old Deletes/Puts get dropped, and old Gets are retired with a kNotFound.
This helps bound the amount of memory consumed by queued operations when the cache gets wedged. Note that when CacheBatcher is layered above AsyncCache, it will queue up its Gets at a level above this one, and ultimately send those using a MultiGet.
1.8.6