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Diffstat (limited to 'chromium/base/metrics/stats_table.h')
| -rw-r--r-- | chromium/base/metrics/stats_table.h | 220 |
1 files changed, 0 insertions, 220 deletions
diff --git a/chromium/base/metrics/stats_table.h b/chromium/base/metrics/stats_table.h deleted file mode 100644 index 719e6304813..00000000000 --- a/chromium/base/metrics/stats_table.h +++ /dev/null @@ -1,220 +0,0 @@ -// Copyright (c) 2011 The Chromium Authors. All rights reserved. -// Use of this source code is governed by a BSD-style license that can be -// found in the LICENSE file. -// -// A StatsTable is a table of statistics. It can be used across multiple -// processes and threads, maintaining cheap statistics counters without -// locking. -// -// The goal is to make it very cheap and easy for developers to add -// counters to code, without having to build one-off utilities or mechanisms -// to track the counters, and also to allow a single "view" to display -// the contents of all counters. -// -// To achieve this, StatsTable creates a shared memory segment to store -// the data for the counters. Upon creation, it has a specific size -// which governs the maximum number of counters and concurrent -// threads/processes which can use it. -// - -#ifndef BASE_METRICS_STATS_TABLE_H_ -#define BASE_METRICS_STATS_TABLE_H_ - -#include <string> - -#include "base/base_export.h" -#include "base/basictypes.h" -#include "base/containers/hash_tables.h" -#include "base/memory/shared_memory.h" -#include "base/synchronization/lock.h" -#include "base/threading/thread_local_storage.h" -#include "build/build_config.h" - -#if defined(OS_POSIX) -#include "base/file_descriptor_posix.h" -#endif - -namespace base { - -class BASE_EXPORT StatsTable { - public: - // Identifies a StatsTable. We often want to share these between processes. - // - // On Windows, we use a named shared memory segment so the table identifier - // should be a relatively unique string identifying the table to use. An - // empty string can be used to use an anonymous shared memory segment for - // cases where the table does not need to be shared between processes. - // - // Posix does not support named memory so we explicitly share file - // descriptors. On Posix, pass a default-constructed file descriptor if a - // handle doesn't already exist, and a new one will be created. - // - // If a table doesn't already exist with the given identifier, a new one will - // be created with zeroed counters. -#if defined(OS_POSIX) - typedef FileDescriptor TableIdentifier; -#elif defined(OS_WIN) - typedef std::string TableIdentifier; -#endif - - // Create a new StatsTable. - // - // max_threads is the maximum number of threads the table will support. - // If the StatsTable already exists, this number is ignored. - // - // max_counters is the maximum number of counters the table will support. - // If the StatsTable already exists, this number is ignored. - StatsTable(const TableIdentifier& table, - int max_threads, - int max_counters); - - // Destroys the StatsTable. When the last StatsTable is destroyed - // (across all processes), the StatsTable is removed from disk. - ~StatsTable(); - - // For convenience, we create a static table. This is generally - // used automatically by the counters. - static StatsTable* current(); - - // Set the global table for use in this process. - static void set_current(StatsTable* value); - - // Get the slot id for the calling thread. Returns 0 if no - // slot is assigned. - int GetSlot() const; - - // All threads that contribute data to the table must register with the - // table first. This function will set thread local storage for the - // thread containing the location in the table where this thread will - // write its counter data. - // - // name is just a debugging tag to label the thread, and it does not - // need to be unique. It will be truncated to kMaxThreadNameLength-1 - // characters. - // - // On success, returns the slot id for this thread. On failure, - // returns 0. - int RegisterThread(const std::string& name); - - // Returns the number of threads currently registered. This is really not - // useful except for diagnostics and debugging. - int CountThreadsRegistered() const; - - // Find a counter in the StatsTable. - // - // Returns an id for the counter which can be used to call GetLocation(). - // If the counter does not exist, attempts to create a row for the new - // counter. If there is no space in the table for the new counter, - // returns 0. - int FindCounter(const std::string& name); - - // TODO(mbelshe): implement RemoveCounter. - - // Gets the location of a particular value in the table based on - // the counter id and slot id. - int* GetLocation(int counter_id, int slot_id) const; - - // Gets the counter name at a particular row. If the row is empty, - // returns NULL. - const char* GetRowName(int index) const; - - // Gets the sum of the values for a particular row. - int GetRowValue(int index) const; - - // Gets the sum of the values for a particular row for a given pid. - int GetRowValue(int index, int pid) const; - - // Gets the sum of the values for a particular counter. If the counter - // does not exist, creates the counter. - int GetCounterValue(const std::string& name); - - // Gets the sum of the values for a particular counter for a given pid. - // If the counter does not exist, creates the counter. - int GetCounterValue(const std::string& name, int pid); - - // The maxinum number of counters/rows in the table. - int GetMaxCounters() const; - - // The maxinum number of threads/columns in the table. - int GetMaxThreads() const; - -#if defined(OS_POSIX) - // Get the underlying shared memory handle for the table. - base::SharedMemoryHandle GetSharedMemoryHandle() const; -#endif - - // The maximum length (in characters) of a Thread's name including - // null terminator, as stored in the shared memory. - static const int kMaxThreadNameLength = 32; - - // The maximum length (in characters) of a Counter's name including - // null terminator, as stored in the shared memory. - static const int kMaxCounterNameLength = 64; - - // Convenience function to lookup a counter location for a - // counter by name for the calling thread. Will register - // the thread if it is not already registered. - static int* FindLocation(const char *name); - - private: - class Internal; - struct TLSData; - typedef hash_map<std::string, int> CountersMap; - - // Returns the space occupied by a thread in the table. Generally used - // if a thread terminates but the process continues. This function - // does not zero out the thread's counters. - // Cannot be used inside a posix tls destructor. - void UnregisterThread(); - - // This variant expects the tls data to be passed in, so it is safe to - // call from inside a posix tls destructor (see doc for pthread_key_create). - void UnregisterThread(TLSData* tls_data); - - // The SlotReturnFunction is called at thread exit for each thread - // which used the StatsTable. - static void SlotReturnFunction(void* data); - - // Locates a free slot in the table. Returns a number > 0 on success, - // or 0 on failure. The caller must hold the shared_memory lock when - // calling this function. - int FindEmptyThread() const; - - // Locates a counter in the table or finds an empty row. Returns a - // number > 0 on success, or 0 on failure. The caller must hold the - // shared_memory_lock when calling this function. - int FindCounterOrEmptyRow(const std::string& name) const; - - // Internal function to add a counter to the StatsTable. Assumes that - // the counter does not already exist in the table. - // - // name is a unique identifier for this counter, and will be truncated - // to kMaxCounterNameLength-1 characters. - // - // On success, returns the counter_id for the newly added counter. - // On failure, returns 0. - int AddCounter(const std::string& name); - - // Get the TLS data for the calling thread. Returns NULL if none is - // initialized. - TLSData* GetTLSData() const; - - Internal* internal_; - - // The counters_lock_ protects the counters_ hash table. - base::Lock counters_lock_; - - // The counters_ hash map is an in-memory hash of the counters. - // It is used for quick lookup of counters, but is cannot be used - // as a substitute for what is in the shared memory. Even though - // we don't have a counter in our hash table, another process may - // have created it. - CountersMap counters_; - ThreadLocalStorage::Slot tls_index_; - - DISALLOW_COPY_AND_ASSIGN(StatsTable); -}; - -} // namespace base - -#endif // BASE_METRICS_STATS_TABLE_H_ |