xpcom/build/perfprobe.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /**
   8  * A mechanism for interacting with operating system-provided
   9  * debugging/profiling tools such as Microsoft EWT/Windows Performance Toolkit.
  10  */
  11
  12 #ifndef mozilla_perfprobe_h
  13 #define mozilla_perfprobe_h
  14
  15 #if !defined(XP_WIN)
  16 #  error "For the moment, perfprobe.h is defined only for Windows platforms"
  17 #endif
  18
  19 #include "nsError.h"
  20 #include "nsString.h"
  21 #include "mozilla/Logging.h"
  22 #include "nsTArray.h"
  23 #include <windows.h>
  24 #undef GetStartupInfo  // Prevent Windows from polluting global namespace
  25 #include <wmistr.h>
  26 #include <evntrace.h>
  27
  28 namespace mozilla {
  29 namespace probes {
  30
  31 class ProbeManager;
  32
  33 /**
  34  * A data structure supporting a trigger operation that can be used to
  35  * send information to the operating system.
  36  */
  37
  38 class Probe {
  39  public:
  40   NS_INLINE_DECL_REFCOUNTING(Probe)
  41
  42   /**
  43    * Trigger the event.
  44    *
  45    * Note: Can be called from any thread.
  46    */
  47   nsresult Trigger();
  48
  49  protected:
  50   ~Probe() {};
  51
  52   Probe(const nsCID& aGUID, const nsACString& aName, ProbeManager* aManager);
  53   friend class ProbeManager;
  54
  55  protected:
  56   /**
  57    * The system GUID associated to this probe. See the documentation
  58    * of |ProbeManager::Make| for more details.
  59    */
  60   const GUID mGUID;
  61
  62   /**
  63    * The name of this probe. See the documentation
  64    * of |ProbeManager::Make| for more details.
  65    */
  66   const nsCString mName;
  67
  68   /**
  69    * The ProbeManager managing this probe.
  70    *
  71    * Note: This is a weak reference to avoid a useless cycle.
  72    */
  73   class ProbeManager* mManager;
  74 };
  75
  76 /**
  77  * A manager for a group of probes.
  78  *
  79  * You can have several managers in one application, provided that they all
  80  * have distinct IDs and names. However, having more than 2 is considered a bad
  81  * practice.
  82  */
  83 class ProbeManager {
  84  public:
  85   NS_INLINE_DECL_REFCOUNTING(ProbeManager)
  86
  87   /**
  88    * Create a new probe manager.
  89    *
  90    * This constructor should be called from the main thread.
  91    *
  92    * @param aApplicationUID The unique ID of the probe. Under Windows, this
  93    * unique ID must have been previously registered using an external tool.
  94    * See MyCategory on http://msdn.microsoft.com/en-us/library/aa364100.aspx
  95    * @param aApplicationName A name for the probe. Currently used only for
  96    * logging purposes. In the future, may be attached to the data sent to the
  97    * operating system.
  98    *
  99    * Note: If two ProbeManagers are constructed with the same uid and/or name,
 100    * behavior is unspecified.
 101    */
 102   ProbeManager(const nsCID& aApplicationUID,
 103                const nsACString& aApplicationName);
 104
 105   /**
 106    * Acquire a probe.
 107    *
 108    * Note: Only probes acquired before the call to SetReady are taken into
 109    * account
 110    * Note: Can be called only from the main thread.
 111    *
 112    * @param aEventUID The unique ID of the probe. Under Windows, this unique
 113    * ID must have been previously registered using an external tool.
 114    * See MyCategory on http://msdn.microsoft.com/en-us/library/aa364100.aspx
 115    * @param aEventName A name for the probe. Currently used only for logging
 116    * purposes. In the
 117    * future, may be attached to the data sent to the operating system.
 118    * @return Either |null| in case of error or a valid |Probe*|.
 119    *
 120    * Note: If this method is called twice with the same uid and/or name,
 121    * behavior is undefined.
 122    */
 123   already_AddRefed<Probe> GetProbe(const nsCID& aEventUID,
 124                                    const nsACString& aEventName);
 125
 126   /**
 127    * Start/stop the measuring session.
 128    *
 129    * This method should be called from the main thread.
 130    *
 131    * Note that starting an already started probe manager has no effect,
 132    * nor does stopping an already stopped probe manager.
 133    */
 134   nsresult StartSession();
 135   nsresult StopSession();
 136
 137   /**
 138    * @return true If measures are currently on, i.e. if triggering probes is any
 139    * is useful. You do not have to check this before triggering a probe, unless
 140    * this can avoid complex computations.
 141    */
 142   bool IsActive();
 143
 144  protected:
 145   ~ProbeManager();
 146
 147   nsresult StartSession(nsTArray<RefPtr<Probe>>& aProbes);
 148   nsresult Init(const nsCID& aApplicationUID,
 149                 const nsACString& aApplicationName);
 150
 151  protected:
 152   /**
 153    * `true` if a session is in activity, `false` otherwise.
 154    */
 155   bool mIsActive;
 156
 157   /**
 158    * The UID of this manager.
 159    * See documentation above for registration steps that you
 160    * may have to take.
 161    */
 162   nsCID mApplicationUID;
 163
 164   /**
 165    * The name of the application.
 166    */
 167   nsCString mApplicationName;
 168
 169   /**
 170    * All the probes that have been created for this manager.
 171    */
 172   nsTArray<RefPtr<Probe>> mAllProbes;
 173
 174   /**
 175    * Handle used for triggering events
 176    */
 177   TRACEHANDLE mSessionHandle;
 178
 179   /**
 180    * Handle used for registration/unregistration
 181    */
 182   TRACEHANDLE mRegistrationHandle;
 183
 184   /**
 185    * `true` if initialization has been performed, `false` until then.
 186    */
 187   bool mInitialized;
 188
 189   friend class Probe;  // Needs to access |mSessionHandle|
 190   friend ULONG WINAPI ControlCallback(WMIDPREQUESTCODE aRequestCode,
 191                                       PVOID aContext, ULONG* aReserved,
 192                                       PVOID aBuffer);  // Sets |mSessionHandle|
 193 };
 194
 195 }  // namespace probes
 196 }  // namespace mozilla
 197
 198 #endif  // mozilla_perfprobe_h