tor-browser

The Tor Browser
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Probes.h (2626B)

      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 #ifndef vm_Probes_h
      8 #define vm_Probes_h
      9 
     10 #include "vm/JSObject.h"
     11 
     12 namespace js {
     13 
     14 class InterpreterFrame;
     15 
     16 namespace probes {
     17 
     18 /*
     19 * Static probes
     20 *
     21 * The probe points defined in this file are scattered around the SpiderMonkey
     22 * source tree. The presence of probes::SomeEvent() means that someEvent is
     23 * about to happen or has happened. To the extent possible, probes should be
     24 * inserted in all paths associated with a given event, regardless of the
     25 * active runmode (interpreter/traceJIT/methodJIT/ionJIT).
     26 *
     27 * When a probe fires, it is handled by any probe handling backends that have
     28 * been compiled in. By default, most probes do nothing or at least do nothing
     29 * expensive, so the presence of the probe should have negligible effect on
     30 * running time. (Probes in slow paths may do something by default, as long as
     31 * there is no noticeable slowdown.)
     32 *
     33 * For some probes, the mere existence of the probe is too expensive even if it
     34 * does nothing when called. For example, just having consistent information
     35 * available for a function call entry/exit probe causes the JITs to
     36 * de-optimize function calls. In those cases, the JITs may query at compile
     37 * time whether a probe is desired, and omit the probe invocation if not. If a
     38 * probe is runtime-disabled at compilation time, it is not guaranteed to fire
     39 * within a compiled function if it is later enabled.
     40 *
     41 * Not all backends handle all of the probes listed here.
     42 */
     43 
     44 /*
     45 * Internal use only: remember whether "profiling", whatever that means, is
     46 * currently active. Used for state management.
     47 */
     48 extern bool ProfilingActive;
     49 
     50 /* Entering a JS function */
     51 bool EnterScript(JSContext*, JSScript*, JSFunction*, InterpreterFrame*);
     52 
     53 /* About to leave a JS function */
     54 void ExitScript(JSContext*, JSScript*, JSFunction*, bool popProfilerFrame);
     55 
     56 /*
     57 * Object has been created. |obj| must exist (its class and size are read)
     58 */
     59 bool CreateObject(JSContext* cx, JSObject* obj);
     60 
     61 /*
     62 * Object is about to be finalized. |obj| must still exist (its class is
     63 * read)
     64 */
     65 bool FinalizeObject(JSObject* obj);
     66 }  // namespace probes
     67 
     68 inline bool probes::CreateObject(JSContext* cx, JSObject* obj) { return true; }
     69 
     70 inline bool probes::FinalizeObject(JSObject* obj) { return true; }
     71 
     72 } /* namespace js */
     73 
     74 #endif /* vm_Probes_h */