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      1 # tifast
      2 
      3 tifast is a JVMTI agent designed for profiling the performance impact listening
      4 to various JVMTI events. It is called tifast since none of the event handlers do
      5 anything meaning that it can be considered speed-of-light.
      6 
      7 # Usage
      8 ### Build
      9 >    `make libtifast`
     10 
     11 The libraries will be built for 32-bit, 64-bit, host and target. Below examples
     12 assume you want to use the 64-bit version.
     13 
     14 ### Command Line
     15 
     16 The agent is loaded using -agentpath like normal. It takes arguments in the
     17 following format:
     18 >     `[log,][EventName1[,EventName2[,...]]]`
     19 
     20 * If 'log' is the first argument the event handlers will LOG(INFO) when they are
     21   called. This behavior is static. The no-log methods have no branches and just
     22   immediately return.
     23 
     24 * If 'all' is one of the arguments all events the current runtime is capable of
     25   providing will be listened for and all other arguments (excepting 'log') will
     26   be ignored.
     27 
     28 * The event-names are the same names as are used in the jvmtiEventCallbacks
     29   struct.
     30 
     31 * All required capabilities are automatically gained. No capabilities other than
     32   those needed to listen for the events are gained.
     33 
     34 * Only events which do not require additional function calls to cause delivery
     35   and are sent more than once are supported.
     36 
     37 #### Supported events
     38 
     39 The following events may be listened for with this agent
     40 
     41 * `SingleStep`
     42 
     43 * `MethodEntry`
     44 
     45 * `MethodExit`
     46 
     47 * `NativeMethodBind`
     48 
     49 * `Exception`
     50 
     51 * `ExceptionCatch`
     52 
     53 * `ThreadStart`
     54 
     55 * `ThreadEnd`
     56 
     57 * `ClassLoad`
     58 
     59 * `ClassPrepare`
     60 
     61 * `ClassFileLoadHook`
     62 
     63 * `CompiledMethodLoad`
     64 
     65 * `CompiledMethodUnload`
     66 
     67 * `DynamicCodeGenerated`
     68 
     69 * `DataDumpRequest`
     70 
     71 * `MonitorContendedEnter`
     72 
     73 * `MonitorContendedEntered`
     74 
     75 * `MonitorWait`
     76 
     77 * `MonitorWaited`
     78 
     79 * `ResourceExhausted`
     80 
     81 * `VMObjectAlloc`
     82 
     83 * `GarbageCollectionStart`
     84 
     85 * `GarbageCollectionFinish`
     86 
     87 * `VMStart`
     88 
     89 * `VMInit`
     90 
     91 * `VMDeath`
     92 
     93 All other events cannot be listened for by this agent. Most of these missing
     94 events either require the use of other functions in order to be called
     95 (`FramePop`, `ObjectFree`, etc).
     96 
     97 #### ART
     98 >    `art -Xplugin:$ANDROID_HOST_OUT/lib64/libopenjdkjvmti.so '-agentpath:libtifast.so=MethodEntry' -cp tmp/java/helloworld.dex -Xint helloworld`
     99 
    100 * `-Xplugin` and `-agentpath` need to be used, otherwise the agent will fail during init.
    101 * If using `libartd.so`, make sure to use the debug version of jvmti.
    102 
    103 >    `adb shell setenforce 0`
    104 >
    105 >    `adb push $ANDROID_PRODUCT_OUT/system/lib64/libtifast.so /data/local/tmp/`
    106 >
    107 >    `adb shell am start-activity --attach-agent /data/local/tmp/libtifast.so=MonitorWait,ClassPrepare some.debuggable.apps/.the.app.MainActivity`
    108 
    109 #### RI
    110 >    `java '-agentpath:libtifast.so=MethodEntry' -cp tmp/helloworld/classes helloworld`
    111