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/** |
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* This file is part of the CernVM File System. |
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*/ |
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#ifndef CVMFS_FUSE_EVICT_H_ |
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#define CVMFS_FUSE_EVICT_H_ |
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#include <pthread.h> |
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#include <stdint.h> |
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#include <atomic> |
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#include "bigvector.h" |
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#include "duplex_fuse.h" |
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#include "duplex_testing.h" |
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#include "shortstring.h" |
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#include "util/concurrency.h" |
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#include "util/single_copy.h" |
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namespace glue { |
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class InodeTracker; |
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class DentryTracker; |
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} // namespace glue |
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class MountPoint; |
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/** |
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* This class can poke all known dentries out of the kernel caches. This allows |
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* for faster remount/reload of the fuse module because caches don't need to |
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* drain out by timeout. If the fuse library doesn't provide |
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* fuse_lowlevel_notify_inval_entry, it falls back to waiting for drainout. |
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* |
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* Evicting entries from the cache must be done from a separate thread to |
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* avoid a deadlock in the fuse callbacks (see Fuse documentation). |
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*/ |
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class FuseInvalidator : SingleCopy { |
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friend class T_FuseInvalidator; // for T_FuseInvalidator.SetUp() |
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FRIEND_TEST(T_FuseInvalidator, StartStop); |
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FRIEND_TEST(T_FuseInvalidator, InvalidateTimeout); |
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FRIEND_TEST(T_FuseInvalidator, InvalidateOps); |
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public: |
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static bool HasFuseNotifyInval(); |
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/** |
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* Used to track the progress of an "invalidation" request. The invalidator |
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* will evict cache entries for a duration given by the timeout. For very |
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* large caches, active eviction can take longer than the timeout. |
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* |
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* The caller needs to keep Handle active until IsDone() is true; |
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*/ |
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class Handle : SingleCopy { |
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friend class FuseInvalidator; |
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public: |
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explicit Handle(unsigned timeout_s); |
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~Handle(); |
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bool IsDone() const { return status_->load() == 1; } |
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void Reset() { status_->store(0); } |
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void WaitFor(); |
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private: |
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void SetDone() { |
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int32_t expected_val = 0; |
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status_->compare_exchange_strong(expected_val, 1); |
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} |
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unsigned timeout_s_; |
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std::atomic<int32_t> *status_; |
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}; |
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struct Command { |
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virtual ~Command() { } |
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}; |
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struct QuitCommand : public Command { }; |
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struct InvalInodesCommand : public Command { |
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Handle *handle; |
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}; |
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struct InvalDentryCommand : public Command { |
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uint64_t parent_ino; |
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NameString name; |
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}; |
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FuseInvalidator(MountPoint *mountpoint, |
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struct fuse_session **fuse_session, |
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bool fuse_notify_invalidation); |
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~FuseInvalidator(); |
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void Spawn(); |
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void InvalidateInodes(Handle *handle); |
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void InvalidateDentry(uint64_t parent_ino, const NameString &name); |
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private: |
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/** |
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* CONSTRUCTOR ONLY FOR UNITTESTS - mountpoint will illegally be null |
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* ( we do not want to construct a full mountpoint in the unittest ) |
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*/ |
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FuseInvalidator(glue::InodeTracker *inode_tracker, |
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glue::DentryTracker *dentry_tracker, |
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struct fuse_session **fuse_session, |
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bool fuse_notify_invalidation); |
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/** |
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* Add one second to the caller-provided timeout to be on the safe side. |
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*/ |
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static const unsigned kTimeoutSafetyMarginSec; // = 1; |
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/** |
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* If caches are drained out by timeout, set a polling interval. |
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*/ |
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static const unsigned kCheckTimeoutFreqMs; // = 100; |
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/** |
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* If caches are actively drained out, check every so many operations if the |
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* caches are anyway drained out by timeout. |
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*/ |
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static const unsigned kCheckTimeoutFreqOps; // = 256 |
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static void *MainInvalidator(void *data); |
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MountPoint *mount_point_; |
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glue::InodeTracker *inode_tracker_; |
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glue::DentryTracker *dentry_tracker_; |
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struct fuse_session **fuse_session_; |
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bool spawned_; |
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Channel<Command> channel_; |
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pthread_t thread_invalidator_; |
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/** |
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* An invalidation run can take some time. Allow for early cancellation if |
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* thread should be shut down. |
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*/ |
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std::atomic<int32_t> terminated_; |
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BigVector<uint64_t> evict_list_; |
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static bool g_fuse_notify_invalidation_; |
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}; // class FuseInvalidator |
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#endif // CVMFS_FUSE_EVICT_H_ |
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