Full Code of odnoklassniki/jvmti-tools for AI

Repository: odnoklassniki/jvmti-tools
Branch: master
Commit: 477d2391b02f
Files: 10
Total size: 45.3 KB

Directory structure:
gitextract_hu58l01j/

├── .gitignore
├── LICENSE
├── README.md
├── antimodule/
│   └── antimodule.cpp
├── faketime/
│   └── faketime.cpp
├── heapsampler/
│   └── heapsampler.cpp
├── richNPE/
│   └── richNPE.cpp
├── stackframe/
│   ├── StackFrame.java
│   └── stackframe.cpp
└── vmtrace/
    └── vmtrace.cpp

================================================
FILE CONTENTS
================================================

================================================
FILE: .gitignore
================================================
# Compiled class file
*.class

# Log file
*.log

# BlueJ files
*.ctxt

# Mobile Tools for Java (J2ME)
.mtj.tmp/

# Package Files #
*.jar
*.war
*.nar
*.ear
*.zip
*.tar.gz
*.rar

# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
hs_err_pid*


================================================
FILE: LICENSE
================================================
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================================================
FILE: README.md
================================================
# JVM TI tools

Collection of small Java serviceability improvements based on
[JVM Tool Interface](https://docs.oracle.com/en/java/javase/11/docs/specs/jvmti.html).

 - [richNPE](#richnpe)
 - [vmtrace](#vmtrace)
 - [antimodule](#antimodule)
 - [heapsampler](#heapsampler)
 - [faketime](#faketime)

## richNPE

Enhances `NullPointerException` thrown by JVM with a detailed error message.

For example, there are several reasons why the following code may throw `NullPointerException`:

    long value = source.map().get(key);
    
Either

  - `source` is null, or
  - `map()` returns null, or
  - `get()` returns null and the subsequent unboxing fails.
  
The standard JDK exception message does not give a clue which expression exactly caused NPE,
but when using this tool, the message will look like

    java.lang.NullPointerException: Called method 'get()' on null object at bci 19

While [JDK-8218628](https://bugs.openjdk.java.net/browse/JDK-8218628) is going to be implemented
in JDK 13, the given agent improves NPE messages for existing JDK 8-12. 

#### Compilation

    # Linux
    g++ -O2 -fPIC -shared -I $JAVA_HOME/include -I $JAVA_HOME/include/linux -olibrichNPE.so richNPE.cpp
    
    # Windows
    cl /O2 /LD /I "%JAVA_HOME%/include" -I "%JAVA_HOME%/include/win32" richNPE.cpp

#### Usage

    java -agentpath:/path/to/librichNPE.so MainClass


## vmtrace

Traces basic JVM events like

 - Thread started / terminated
 - GC started / finished
 - Class loading / class prepared
 - Method compiled / unloaded
 - Dynamic code generated

#### Example output

```text
[0.05588] Method compiled: java/lang/String.<init> (1056 bytes)
[0.05597] Loading class: java/io/FileOutputStream$1 (557 bytes)
[0.05600] Class prepared: java/io/FileOutputStream$1
[0.05602] Method compiled: java/lang/String.hashCode (512 bytes)
[0.05618] Thread started: main
[0.05622] Loading class: sun/launcher/LauncherHelper (14692 bytes)
[0.05640] Dynamic code generated: I2C/C2I adapters(0xabbebebea0000000)@0x00000000032c38a0 (392 bytes)
[0.05642] Dynamic code generated: I2C/C2I adapters(0xbebebea0)@0x00000000032c36a0 (376 bytes)
...
```

#### Compilation

    # Linux
    g++ -O2 -fPIC -shared -I $JAVA_HOME/include -I $JAVA_HOME/include/linux -olibvmtrace.so vmtrace.cpp
    
    # Windows
    cl /O2 /LD /I "%JAVA_HOME%/include" -I "%JAVA_HOME%/include/win32" vmtrace.cpp

#### Usage

    java -agentpath:/path/to/libvmtrace.so[=output.log] MainClass

The log will be written to the file specified in the agent arguments,
or to `stderr` if no arguments given.


## antimodule

Removes Jigsaw restrictions in JDK 9+ by opening and exporting all
JDK modules to the unnamed module.

This allows Reflection access to all JDK private fields and methods
with no warnings, even when `--illegal-access=deny` option specified.
This also makes all JDK internal classes like `sun.nio.ch.DirectBuffer`
accessible by the unnamed module.

The agent is helpful for running older Java applications on JDK 9+
when application uses private APIs.

#### Compilation

    # Linux
    g++ -O2 -fPIC -shared -I $JAVA_HOME/include -I $JAVA_HOME/include/linux -olibantimodule.so antimodule.cpp
    
    # Windows
    cl /O2 /LD /I "%JAVA_HOME%/include" -I "%JAVA_HOME%/include/win32" antimodule.cpp

#### Usage

    java -agentpath:/path/to/libantimodule.so MainClass


## heapsampler

The example of low-overhead heap allocation profiler based on
[JEP 331](https://openjdk.java.net/jeps/331).

Requires JDK 11 or later.

#### Example output

The output is generated in collapsed stacktraces format suitable for
generating [Flame Graphs](https://github.com/brendangregg/FlameGraph/).

```text
Allocate.main;java.lang.Long.valueOf;java.lang.Long 49
Allocate.main;java.lang.Object[] 31
java.lang.Thread.run;jdk.internal.misc.Signal$1.run;java.lang.Terminator$1.handle;java.lang.Class 1
jdk.internal.misc.Signal.dispatch;java.lang.Class 1
```

See [async-profiler](https://github.com/jvm-profiling-tools/async-profiler)
for more information about allocation profiling and Flame Graphs.
Note that `heapsampler` works only on JDK 11+, while `async-profiler`
is capable of generating allocation profiles on JDK 7+.

#### Compilation

    # Linux
    g++ -O2 -fPIC -shared -I $JAVA_HOME/include -I $JAVA_HOME/include/linux -olibheapsampler.so heapsampler.cpp
    
    # Windows
    cl /O2 /LD /I "%JAVA_HOME%/include" -I "%JAVA_HOME%/include/win32" heapsampler.cpp

#### Usage

    java -agentpath:/path/to/libheapsampler.so[=interval] MainClass > output.txt

The agent can be also loaded dynamically in run-time:

    jcmd <pid> JVMTI.agent_load /path/to/libheapsampler.so [interval]

The optional `interval` argument specifies the sampling interval in bytes.
The default value is 512 KB.
The output is printed on `stdout`.


## faketime

Changes current date/time for a Java application without affecting system date/time.

The agent rebinds the native entry for `System.currentTimeMillis` and related methods
and adds the specified offset to the times returned by these methods.

#### Compilation

    # Linux
    g++ -O2 -fPIC -shared -I $JAVA_HOME/include -I $JAVA_HOME/include/linux -olibfaketime.so faketime.cpp
    
    # Windows
    cl /O2 /LD /I "%JAVA_HOME%/include" -I "%JAVA_HOME%/include/win32" faketime.cpp

#### Usage

    java -agentpath:/path/to/libfaketime.so=timestamp|+-offset MainClass

where the agent argument is either

 - absolute `timestamp` in milliseconds from Epoch, or
 - relative `offset` in milliseconds, if `offset` starts with `+` or `-`

Since `System.currentTimeMillis` is a JVM intrinsic method, it's also required to disable
the corresponding intrinsic to make sure the JNI method is called:

    java -XX:+UnlockDiagnosticVMOptions -XX:DisableIntrinsic=_currentTimeMillis -XX:CompileCommand=dontinline,java.lang.System::currentTimeMillis


================================================
FILE: antimodule/antimodule.cpp
================================================
/*
 * Copyright 2019 Odnoklassniki Ltd, Mail.Ru Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <jvmti.h>
#include <string.h>

void JNICALL VMInit(jvmtiEnv* jvmti, JNIEnv* env, jthread thread) {
    jclass Module = env->FindClass("java/lang/Module");
    if (Module == NULL) {
        // Seems like pre-module JDK
        env->ExceptionClear();
        return;
    }

    jmethodID getPackages = env->GetMethodID(Module, "getPackages", "()Ljava/util/Set;");

    jmethodID getUnnamedModule = env->GetMethodID(
        env->FindClass("java/lang/ClassLoader"), "getUnnamedModule", "()Ljava/lang/Module;");

    jmethodID toString = env->GetMethodID(
        env->FindClass("java/lang/Object"), "toString", "()Ljava/lang/String;");

    // Get unnamed module of the current thread's ClassLoader
    jvmtiThreadInfo thread_info;
    jvmti->GetThreadInfo(NULL, &thread_info);

    jobject unnamed_module = env->CallObjectMethod(thread_info.context_class_loader, getUnnamedModule);

    jint module_count = 0;
    jobject* modules = NULL;
    jvmti->GetAllModules(&module_count, &modules);

    // Scan all loaded modules
    for (int i = 0; i < module_count; i++) {
        jvmti->AddModuleReads(modules[i], unnamed_module);

        // Get all module packages as one string: "[java.lang, java.io, ...]"
        jobject packages = env->CallObjectMethod(modules[i], getPackages);
        jstring str = (jstring) env->CallObjectMethod(packages, toString);

        char* c_str = (char*) env->GetStringUTFChars(str, NULL);
        if (c_str == NULL) continue;

        // Export and open every package to the unnamed module
        char* package = strtok(c_str + 1, ", ]");
        while (package != NULL) {
            jvmti->AddModuleExports(modules[i], package, unnamed_module);
            jvmti->AddModuleOpens(modules[i], package, unnamed_module);
            package = strtok(NULL, ", ]");
        }

        env->ReleaseStringUTFChars(str, c_str);
    }

    jvmti->Deallocate((unsigned char*) modules);
}

JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM* vm, char* options, void* reserved) {
    jvmtiEnv* jvmti;
    vm->GetEnv((void**) &jvmti, JVMTI_VERSION_1_0);

    jvmtiEventCallbacks callbacks = {0};
    callbacks.VMInit = VMInit;
    jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks));
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_INIT, NULL);

    return 0;
}


================================================
FILE: faketime/faketime.cpp
================================================
/*
 * Copyright 2020 Odnoklassniki Ltd, Mail.Ru Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <jvmti.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

static jlong (*real_time_millis)(JNIEnv*, jclass) = NULL;
static jlong (*real_nano_time_adjustment)(JNIEnv*, jclass, jlong) = NULL;
static jlong offset_millis = 0;

jlong JNICALL fake_time_millis(JNIEnv* env, jclass cls) {
    return real_time_millis(env, cls) + offset_millis;
}

jlong JNICALL fake_nano_time_adjustment(JNIEnv* env, jclass cls, jlong offset_seconds) {
    return real_nano_time_adjustment(env, cls, offset_seconds) + offset_millis * 1000000;
}

void JNICALL NativeMethodBind(jvmtiEnv* jvmti, JNIEnv* env, jthread thread, jmethodID method,
                              void* address, void** new_address_ptr) {
    char* name;
    if (jvmti->GetMethodName(method, &name, NULL, NULL) == 0) {
        if (real_time_millis == NULL && strcmp(name, "currentTimeMillis") == 0) {
            real_time_millis = (jlong (*)(JNIEnv*, jclass)) address;
            *new_address_ptr = (void*) fake_time_millis;
        } else if (real_nano_time_adjustment == NULL && strcmp(name, "getNanoTimeAdjustment") == 0) {
            real_nano_time_adjustment = (jlong (*)(JNIEnv*, jclass, jlong)) address;
            *new_address_ptr = (void*) fake_nano_time_adjustment;
        }
        jvmti->Deallocate((unsigned char*) name);
    }
}

JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM* vm, char* options, void* reserved) {
    if (options != NULL) {
        if (options[0] == '+' || options[0] == '-') {
            offset_millis = atoll(options);                        // time offset
        } else {
            offset_millis = atoll(options) - time(NULL) * 1000LL;  // absolute time
        }
    }

    jvmtiEnv* jvmti;
    vm->GetEnv((void**) &jvmti, JVMTI_VERSION_1_0);

    jvmtiCapabilities capabilities = {0};
    capabilities.can_generate_native_method_bind_events = 1;
#if JNI_VERSION_9
    jvmtiCapabilities potential_capabilities;
    jvmti->GetPotentialCapabilities(&potential_capabilities);
    capabilities.can_generate_early_vmstart = potential_capabilities.can_generate_early_vmstart;
#endif
    jvmti->AddCapabilities(&capabilities);

    jvmtiEventCallbacks callbacks = {0};
    callbacks.NativeMethodBind = NativeMethodBind;
    jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks));

    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_NATIVE_METHOD_BIND, NULL);

    return 0;
}


================================================
FILE: heapsampler/heapsampler.cpp
================================================
/*
 * Copyright 2019 Odnoklassniki Ltd, Mail.Ru Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <jvmti.h>
#include <cstdlib>
#include <cstring>
#include <map>
#include <string>
#include <iostream>

#define MAX_STACK_DEPTH 1024

struct Frame {
    jlong samples;
    jlong bytes;
    std::map<jmethodID, Frame> children;
};

static jvmtiEnv* jvmti = NULL;
static jrawMonitorID tree_lock;
static std::map<std::string, Frame> root;

// Converts JVM internal class signature to human readable name
static std::string decode_class_signature(char* class_sig) {
    switch (class_sig[0]) {
        case 'B': return "byte";
        case 'C': return "char";
        case 'S': return "short";
        case 'I': return "int";
        case 'J': return "long";
        case 'F': return "float";
        case 'D': return "double";
        case 'Z': return "boolean";
        case '[': return decode_class_signature(class_sig + 1) + "[]";
    }

    // Strip 'L' and ';'
    class_sig++;
    class_sig[std::strlen(class_sig) - 1] = 0;

    // Replace '/' with '.'
    for (char* c = class_sig; *c; c++) {
        if (*c == '/') *c = '.';
    }

    return class_sig;
}

static std::string get_method_name(jmethodID method) {
    jclass method_class;
    char* class_sig = NULL;
    char* method_name = NULL;
    std::string result;

    if (jvmti->GetMethodDeclaringClass(method, &method_class) == 0 &&
        jvmti->GetClassSignature(method_class, &class_sig, NULL) == 0 &&
        jvmti->GetMethodName(method, &method_name, NULL, NULL) == 0) {
        result.assign(decode_class_signature(class_sig) + "." + method_name);
    } else {
        result.assign("[unknown]");
    }

    jvmti->Deallocate((unsigned char*) method_name);
    jvmti->Deallocate((unsigned char*) class_sig);
    return result;
}

static void dump_tree(const std::string stack_line, const std::string& class_name, const Frame* f) {
    if (f->samples > 0) {
        // Output sample in 'collapsed stack traces' format understood by flamegraph.pl
        std::cout << stack_line << class_name << "_[i] " << f->samples << std::endl;
    }
    for (auto it = f->children.begin(); it != f->children.end(); ++it) {
        dump_tree(stack_line + get_method_name(it->first) + ";", class_name, &it->second);
    }
}

static void dump_profile() {
    for (auto it = root.begin(); it != root.end(); ++it) {
        dump_tree("", it->first, &it->second);
    }
}

static void record_stack_trace(char* class_sig, jvmtiFrameInfo* frames, jint count, jlong size) {
    Frame* f = &root[decode_class_signature(class_sig)];
    while (--count >= 0) {
        f = &f->children[frames[count].method];
    }
    f->samples++;
    f->bytes += size;
}

void JNICALL SampledObjectAlloc(jvmtiEnv* jvmti, JNIEnv* env, jthread thread,
                                jobject object, jclass object_klass, jlong size) {

    jvmtiFrameInfo frames[MAX_STACK_DEPTH];
    jint count;
    if (jvmti->GetStackTrace(thread, 0, MAX_STACK_DEPTH, frames, &count) != 0) {
        return;
    }

    char* class_sig;
    if (jvmti->GetClassSignature(object_klass, &class_sig, NULL) != 0) {
        return;
    }

    jvmti->RawMonitorEnter(tree_lock);
    record_stack_trace(class_sig, frames, count, size);
    jvmti->RawMonitorExit(tree_lock);

    jvmti->Deallocate((unsigned char*) class_sig);
}

void JNICALL DataDumpRequest(jvmtiEnv* jvmti) {
    jvmti->RawMonitorEnter(tree_lock);
    dump_profile();
    jvmti->RawMonitorExit(tree_lock);
}

void JNICALL VMDeath(jvmtiEnv* jvmti, JNIEnv* env) {
    DataDumpRequest(jvmti);
}

JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM* vm, char* options, void* reserved) {
    vm->GetEnv((void**) &jvmti, JVMTI_VERSION_1_0);

    jvmti->CreateRawMonitor("tree_lock", &tree_lock);

    jvmtiCapabilities capabilities = {0};
    capabilities.can_generate_sampled_object_alloc_events = 1;
    jvmti->AddCapabilities(&capabilities);

    if (options != NULL && options[0] >= '0' && options[0] <= '9') {
        jvmti->SetHeapSamplingInterval(std::atoi(options));
    }

    jvmtiEventCallbacks callbacks = {0};
    callbacks.SampledObjectAlloc = SampledObjectAlloc;
    callbacks.DataDumpRequest = DataDumpRequest;
    callbacks.VMDeath = VMDeath;
    jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks));
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_SAMPLED_OBJECT_ALLOC, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_DATA_DUMP_REQUEST, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_DEATH, NULL);

    return 0;
}

JNIEXPORT jint JNICALL Agent_OnAttach(JavaVM* vm, char* options, void* reserved) {
    // Protect against repeated load
    if (jvmti != NULL) {
        return 0;
    }
    return Agent_OnLoad(vm, options, reserved);
}


================================================
FILE: richNPE/richNPE.cpp
================================================
/*
 * Copyright 2019 Odnoklassniki Ltd, Mail.Ru Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <jvmti.h>
#include <classfile_constants.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef unsigned char u1;
typedef unsigned short u2;

static const char* get_exception_message(u1 bytecode) {
    switch (bytecode) {
        case JVM_OPC_iaload: return "Load from null int array at bci %d";
        case JVM_OPC_laload: return "Load from null long array at bci %d";
        case JVM_OPC_faload: return "Load from null float array at bci %d";
        case JVM_OPC_daload: return "Load from null double array at bci %d";
        case JVM_OPC_aaload: return "Load from null Object array at bci %d";
        case JVM_OPC_baload: return "Load from null byte/boolean array at bci %d";
        case JVM_OPC_caload: return "Load from null char array at bci %d";
        case JVM_OPC_saload: return "Load from null short array at bci %d";

        case JVM_OPC_iastore: return "Store into null int array at bci %d";
        case JVM_OPC_lastore: return "Store into null long array at bci %d";
        case JVM_OPC_fastore: return "Store into null float array at bci %d";
        case JVM_OPC_dastore: return "Store into null double array at bci %d";
        case JVM_OPC_aastore: return "Store into null Object array at bci %d";
        case JVM_OPC_bastore: return "Store into null byte/boolean array at bci %d";
        case JVM_OPC_castore: return "Store into null char array at bci %d";
        case JVM_OPC_sastore: return "Store into null short array at bci %d";

        case JVM_OPC_arraylength: return "Get .length of null array";

        case JVM_OPC_getfield: return "Get field '%s' of null object at bci %d";
        case JVM_OPC_putfield: return "Put field '%s' of null object at bci %d";

        case JVM_OPC_invokevirtual: // fall through
        case JVM_OPC_invokespecial: // fall through
        case JVM_OPC_invokeinterface: return "Called method '%s' on null object at bci %d";

        case JVM_OPC_monitorenter: // fall through
        case JVM_OPC_monitorexit: return "Synchronized on null monitor at bci %d";

        default: return NULL;
    }
}

static u2 get_u2(const u1* bytes) {
    return bytes[0] << 8 | bytes[1];
}

static u1* get_cpool_at(u1* cpool, u2 index) {
    // Length in bytes of a constant pool item with the given tag
    static u1 cp_item_size[] = {0, 3, 0, 5, 5, 9, 9, 3, 3, 5, 5, 5, 5, 4, 3, 5, 5, 3, 3};

    for (unsigned int i = 1; i < index; i++) {
        u1 tag = cpool[0];
        cpool += tag == JVM_CONSTANT_Utf8 ? 3 + get_u2(cpool + 1) : cp_item_size[tag];
    }

    return cpool;
}

static char* get_name_from_cpool(jvmtiEnv* jvmti, jmethodID method, const u1* bytecodes) {
    jclass holder;
    jvmti->GetMethodDeclaringClass(method, &holder);

    jint cpool_count;
    jint cpool_bytes;
    u1* cpool;
    if (jvmti->GetConstantPool(holder, &cpool_count, &cpool_bytes, &cpool) != 0) {
        return strdup("<unknown>");
    }

    u1* ref = get_cpool_at(cpool, get_u2(bytecodes + 1));       // CONSTANT_Fieldref / Methodref
    u1* name_and_type = get_cpool_at(cpool, get_u2(ref + 3));   // CONSTANT_NameAndType
    u1* name = get_cpool_at(cpool, get_u2(name_and_type + 1));  // CONSTANT_Utf8

    size_t name_length = get_u2(name + 1);
    char* result = (char*) malloc(name_length + 1);
    memcpy(result, name + 3, name_length);
    result[name_length] = 0;

    jvmti->Deallocate(cpool);
    return result;
}


// Cache JNI handles as soon as VM initializes
static jclass NullPointerException = NULL;
static jfieldID detailMessage = NULL;

void JNICALL VMInit(jvmtiEnv* jvmti, JNIEnv* env, jthread thread) {
    jclass localNPE = env->FindClass("java/lang/NullPointerException");
    NullPointerException = (jclass) env->NewGlobalRef(localNPE);

    jclass Throwable = env->FindClass("java/lang/Throwable");
    detailMessage = env->GetFieldID(Throwable, "detailMessage", "Ljava/lang/String;");
}

void JNICALL ExceptionCallback(jvmtiEnv* jvmti, JNIEnv* env, jthread thread,
                               jmethodID method, jlocation location, jobject exception,
                               jmethodID catch_method, jlocation catch_location) {

    if (NullPointerException == NULL || detailMessage == NULL ||
        !env->IsInstanceOf(exception, NullPointerException)) {
        return;
    }

    jint bytecode_count;
    u1* bytecodes;
    if (jvmti->GetBytecodes(method, &bytecode_count, &bytecodes) != 0) {
        return;
    }

    if (location >= 0 && location < bytecode_count) {
        const char* message = get_exception_message(bytecodes[location]);
        if (message != NULL) {
            char buf[400];
            if (strstr(message, "%s") != NULL) {
                char* name = get_name_from_cpool(jvmti, method, bytecodes + location);
                snprintf(buf, sizeof(buf), message, name, (int) location);
                free(name);
            } else {
                sprintf(buf, message, (int) location);
            }
            env->SetObjectField(exception, detailMessage, env->NewStringUTF(buf));
        }
    }

    jvmti->Deallocate(bytecodes);
}

JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM* vm, char* options, void* reserved) {
    jvmtiEnv* jvmti;
    vm->GetEnv((void**) &jvmti, JVMTI_VERSION_1_0);

    jvmtiCapabilities capabilities = {0};
    capabilities.can_generate_exception_events = 1;
    capabilities.can_get_bytecodes = 1;
    capabilities.can_get_constant_pool = 1;
    jvmti->AddCapabilities(&capabilities);

    jvmtiEventCallbacks callbacks = {0};
    callbacks.VMInit = VMInit;
    callbacks.Exception = ExceptionCallback;
    jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks));
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_INIT, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_EXCEPTION, NULL);

    return 0;
}


================================================
FILE: stackframe/StackFrame.java
================================================
/*
 * Copyright 2019 Odnoklassniki Ltd, Mail.Ru Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

public class StackFrame {

    static {
        System.loadLibrary("stackframe");
    }

    public static native String getLocation(int depth);
}


================================================
FILE: stackframe/stackframe.cpp
================================================
/*
 * Copyright 2019 Odnoklassniki Ltd, Mail.Ru Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <jvmti.h>
#include <cstdio>
#include <map>

class MethodInfo {
  private:
    char* _file = NULL;
    jvmtiLineNumberEntry* _line_number_table = NULL;
    jint _table_size = 0;
    bool _initialized = false;

  public:
    bool initialized() {
        return _initialized;
    }

    void initialize(jvmtiEnv* jvmti, jmethodID method) {
        jclass method_class;
        if (jvmti->GetMethodDeclaringClass(method, &method_class) == 0) {
            jvmti->GetSourceFileName(method_class, &_file);
        }

        jvmti->GetLineNumberTable(method, &_table_size, &_line_number_table);

        _initialized = true;
    }

    char* file() {
        return _file;
    }

    int line(jlocation location) {
        int line = 0;
        jlocation min = 0xffff;
        for (int i = 0; i < _table_size; i++) {
            jlocation start = _line_number_table[i].start_location;
            if (location >= start && start < min) {
                line = _line_number_table[i].line_number;
                min = start;
            }
        }
        return line;
    }
};

static jvmtiEnv* jvmti;
static std::map<jmethodID, MethodInfo> method_cache;

extern "C" JNIEXPORT jstring JNICALL
Java_StackFrame_getLocation(JNIEnv* env, jclass unused, jint depth) {
    jvmtiFrameInfo frame;
    jint count;
    if (jvmti->GetStackTrace(NULL, depth, 1, &frame, &count) != 0) {
        return NULL;
    }

    MethodInfo* info = &method_cache[frame.method];
    if (!info->initialized()) {
        info->initialize(jvmti, frame.method);
    }

    char buf[1024];
    std::snprintf(buf, sizeof(buf), "%s:%d", info->file(), info->line(frame.location));
    return env->NewStringUTF(buf);
}

jint JNI_OnLoad(JavaVM* vm, void* reserved) {
    vm->GetEnv((void**) &jvmti, JVMTI_VERSION_1_0);

    jvmtiCapabilities capabilities = {0};
    capabilities.can_get_source_file_name = 1;
    capabilities.can_get_line_numbers = 1;
    jvmti->AddCapabilities(&capabilities);

    return JNI_VERSION_1_6;
}


================================================
FILE: vmtrace/vmtrace.cpp
================================================
/*
 * Copyright 2019 Odnoklassniki Ltd, Mail.Ru Group
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <jvmti.h>
#include <stdarg.h>
#include <string.h>
#include <stdio.h>

static FILE* out;
static jrawMonitorID vmtrace_lock;
static jlong start_time;

static void trace(jvmtiEnv* jvmti, const char* fmt, ...) {
    jlong current_time;
    jvmti->GetTime(&current_time);

    char buf[1024];
    va_list args;
    va_start(args, fmt);
    vsnprintf(buf, sizeof(buf), fmt, args);
    va_end(args);

    jvmti->RawMonitorEnter(vmtrace_lock);

    fprintf(out, "[%.5f] %s\n", (current_time - start_time) / 1000000000.0, buf);
    
    jvmti->RawMonitorExit(vmtrace_lock);
}

static char* fix_class_name(char* class_name) {
    // Strip 'L' and ';' from class signature
    class_name[strlen(class_name) - 1] = 0;
    return class_name + 1;
}


class ClassName {
  private:
    jvmtiEnv* _jvmti;
    char* _name;

  public:
    ClassName(jvmtiEnv* jvmti, jclass klass) : _jvmti(jvmti), _name(NULL) {
        _jvmti->GetClassSignature(klass, &_name, NULL);
    }

    ~ClassName() {
        _jvmti->Deallocate((unsigned char*) _name);
    }

    char* name() {
        return _name == NULL ? NULL : fix_class_name(_name);
    }
};

class MethodName {
  private:
    jvmtiEnv* _jvmti;
    char* _holder_name;
    char* _method_name;

  public:
    MethodName(jvmtiEnv* jvmti, jmethodID method) : _jvmti(jvmti),
                                                    _holder_name(NULL),
                                                    _method_name(NULL) {
        jclass holder;
        if (_jvmti->GetMethodDeclaringClass(method, &holder) == 0) {
            _jvmti->GetClassSignature(holder, &_holder_name, NULL);
            _jvmti->GetMethodName(method, &_method_name, NULL, NULL);
        }
    }

    ~MethodName() {
        _jvmti->Deallocate((unsigned char*) _method_name);
        _jvmti->Deallocate((unsigned char*) _holder_name);
    }

    char* holder() {
        return _holder_name == NULL ? NULL : fix_class_name(_holder_name);
    }

    char* name() {
        return _method_name;
    }
};

class ThreadName {
  private:
    jvmtiEnv* _jvmti;
    char* _name;

  public:
    ThreadName(jvmtiEnv* jvmti, jthread thread) : _jvmti(jvmti), _name(NULL) {
        jvmtiThreadInfo info;
        _name = _jvmti->GetThreadInfo(thread, &info) == 0 ? info.name : NULL;
    }

    ~ThreadName() {
        _jvmti->Deallocate((unsigned char*) _name);
    }

    char* name() {
        return _name;
    }
};


void JNICALL VMStart(jvmtiEnv* jvmti, JNIEnv* env) {
    trace(jvmti, "VM started");
}

void JNICALL VMInit(jvmtiEnv* jvmti, JNIEnv* env, jthread thread) {
    trace(jvmti, "VM initialized");
}

void JNICALL VMDeath(jvmtiEnv* jvmti, JNIEnv* env) {
    trace(jvmti, "VM destroyed");
}

void JNICALL ClassFileLoadHook(jvmtiEnv* jvmti, JNIEnv* env,
                               jclass class_being_redefined, jobject loader,
                               const char* name, jobject protection_domain,
                               jint data_len, const unsigned char* data,
                               jint* new_data_len, unsigned char** new_data) {
    trace(jvmti, "Loading class: %s (%d bytes)", name, data_len);
}

void JNICALL ClassPrepare(jvmtiEnv* jvmti, JNIEnv* env,
                          jthread thread, jclass klass) {
    ClassName cn(jvmti, klass);
    trace(jvmti, "Class prepared: %s", cn.name());
}

void JNICALL DynamicCodeGenerated(jvmtiEnv* jvmti, const char* name,
                                  const void* address, jint length) {
    trace(jvmti, "Dynamic code generated: %s (%d bytes)", name, length);
}

void JNICALL CompiledMethodLoad(jvmtiEnv* jvmti, jmethodID method,
                                jint code_size, const void* code_addr,
                                jint map_length, const jvmtiAddrLocationMap* map,
                                const void* compile_info) {
    MethodName mn(jvmti, method);
    trace(jvmti, "Method compiled: %s.%s (%d bytes)", mn.holder(), mn.name(), code_size);
}

void JNICALL CompiledMethodUnload(jvmtiEnv* jvmti, jmethodID method,
                                  const void* code_addr) {
    MethodName mn(jvmti, method);
    trace(jvmti, "Method flushed: %s.%s", mn.holder(), mn.name());
}

void JNICALL ThreadStart(jvmtiEnv* jvmti, JNIEnv* env, jthread thread) {
    ThreadName tn(jvmti, thread);
    trace(jvmti, "Thread started: %s", tn.name());
}

void JNICALL ThreadEnd(jvmtiEnv* jvmti, JNIEnv* env, jthread thread) {
    ThreadName tn(jvmti, thread);
    trace(jvmti, "Thread finished: %s", tn.name());
}

void JNICALL GarbageCollectionStart(jvmtiEnv* jvmti) {
    trace(jvmti, "GC started");
}

void JNICALL GarbageCollectionFinish(jvmtiEnv* jvmti) {
    trace(jvmti, "GC finished");
}

JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM* vm, char* options, void* reserved) {
    if (options == NULL || !options[0]) {
        out = stderr;
    } else if ((out = fopen(options, "w")) == NULL) {
        fprintf(stderr, "Cannot open output file: %s\n", options);
        return 1;
    }

    jvmtiEnv* jvmti;
    vm->GetEnv((void**) &jvmti, JVMTI_VERSION_1_0);

    jvmti->CreateRawMonitor("vmtrace_lock", &vmtrace_lock);
    jvmti->GetTime(&start_time);

    trace(jvmti, "VMTrace started");

    jvmtiCapabilities capabilities = {0};
    capabilities.can_generate_all_class_hook_events = 1;
    capabilities.can_generate_compiled_method_load_events = 1;
    capabilities.can_generate_garbage_collection_events = 1;
    jvmti->AddCapabilities(&capabilities);

    jvmtiEventCallbacks callbacks = {0};
    callbacks.VMStart = VMStart;
    callbacks.VMInit = VMInit;
    callbacks.VMDeath = VMDeath;
    callbacks.ClassFileLoadHook = ClassFileLoadHook;
    callbacks.ClassPrepare = ClassPrepare;
    callbacks.DynamicCodeGenerated = DynamicCodeGenerated;
    callbacks.CompiledMethodLoad = CompiledMethodLoad;
    callbacks.CompiledMethodUnload = CompiledMethodUnload;
    callbacks.ThreadStart = ThreadStart;
    callbacks.ThreadEnd = ThreadEnd;
    callbacks.GarbageCollectionStart = GarbageCollectionStart;
    callbacks.GarbageCollectionFinish = GarbageCollectionFinish;
    jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks));

    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_START, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_INIT, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_DEATH, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_PREPARE, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_DYNAMIC_CODE_GENERATED, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_COMPILED_METHOD_LOAD, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_COMPILED_METHOD_UNLOAD, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_THREAD_START, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_THREAD_END, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_GARBAGE_COLLECTION_START, NULL);
    jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_GARBAGE_COLLECTION_FINISH, NULL);

    return 0;
}

JNIEXPORT void JNICALL Agent_OnUnload(JavaVM* vm) {
    if (out != NULL && out != stderr) {
        fclose(out);
    }
}