www.aleph1.co.uk Git - yaffs-website/blob - node_modules/nan/doc/v8_internals.md

   1 ## V8 internals
   2
   3 The hooks to access V8 internals—including GC and statistics—are different across the supported versions of V8, therefore NAN provides its own hooks that call the appropriate V8 methods.
   4
   5  - <a href="#api_nan_gc_callback"><b><code>NAN_GC_CALLBACK()</code></b></a>
   6  - <a href="#api_nan_add_gc_epilogue_callback"><b><code>Nan::AddGCEpilogueCallback()</code></b></a>
   7  - <a href="#api_nan_remove_gc_epilogue_callback"><b><code>Nan::RemoveGCEpilogueCallback()</code></b></a>
   8  - <a href="#api_nan_add_gc_prologue_callback"><b><code>Nan::AddGCPrologueCallback()</code></b></a>
   9  - <a href="#api_nan_remove_gc_prologue_callback"><b><code>Nan::RemoveGCPrologueCallback()</code></b></a>
  10  - <a href="#api_nan_get_heap_statistics"><b><code>Nan::GetHeapStatistics()</code></b></a>
  11  - <a href="#api_nan_set_counter_function"><b><code>Nan::SetCounterFunction()</code></b></a>
  12  - <a href="#api_nan_set_create_histogram_function"><b><code>Nan::SetCreateHistogramFunction()</code></b></a>
  13  - <a href="#api_nan_set_add_histogram_sample_function"><b><code>Nan::SetAddHistogramSampleFunction()</code></b></a>
  14  - <a href="#api_nan_idle_notification"><b><code>Nan::IdleNotification()</code></b></a>
  15  - <a href="#api_nan_low_memory_notification"><b><code>Nan::LowMemoryNotification()</code></b></a>
  16  - <a href="#api_nan_context_disposed_notification"><b><code>Nan::ContextDisposedNotification()</code></b></a>
  17  - <a href="#api_nan_get_internal_field_pointer"><b><code>Nan::GetInternalFieldPointer()</code></b></a>
  18  - <a href="#api_nan_set_internal_field_pointer"><b><code>Nan::SetInternalFieldPointer()</code></b></a>
  19  - <a href="#api_nan_adjust_external_memory"><b><code>Nan::AdjustExternalMemory()</code></b></a>
  20
  21
  22 <a name="api_nan_gc_callback"></a>
  23 ### NAN_GC_CALLBACK(callbackname)
  24
  25 Use `NAN_GC_CALLBACK` to declare your callbacks for `Nan::AddGCPrologueCallback()` and `Nan::AddGCEpilogueCallback()`. Your new method receives the arguments `v8::GCType type` and `v8::GCCallbackFlags flags`.
  26
  27 ```c++
  28 static Nan::Persistent<Function> callback;
  29
  30 NAN_GC_CALLBACK(gcPrologueCallback) {
  31   v8::Local<Value> argv[] = { Nan::New("prologue").ToLocalChecked() };
  32   Nan::MakeCallback(Nan::GetCurrentContext()->Global(), Nan::New(callback), 1, argv);
  33 }
  34
  35 NAN_METHOD(Hook) {
  36   callback.Reset(args[0].As<Function>());
  37   Nan::AddGCPrologueCallback(gcPrologueCallback);
  38   info.GetReturnValue().Set(info.Holder());
  39 }
  40 ```
  41
  42 <a name="api_nan_add_gc_epilogue_callback"></a>
  43 ### Nan::AddGCEpilogueCallback()
  44
  45 Signature:
  46
  47 ```c++
  48 void Nan::AddGCEpilogueCallback(v8::Isolate::GCEpilogueCallback callback, v8::GCType gc_type_filter = v8::kGCTypeAll)
  49 ```
  50
  51 Calls V8's [`AddGCEpilogueCallback()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#a90d1860babc76059c62514b422f56960).
  52
  53 <a name="api_nan_remove_gc_epilogue_callback"></a>
  54 ### Nan::RemoveGCEpilogueCallback()
  55
  56 Signature:
  57
  58 ```c++
  59 void Nan::RemoveGCEpilogueCallback(v8::Isolate::GCEpilogueCallback callback)
  60 ```
  61
  62 Calls V8's [`RemoveGCEpilogueCallback()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#a05c60859fd4b8e96bfcd451281ed6c7c).
  63
  64 <a name="api_nan_add_gc_prologue_callback"></a>
  65 ### Nan::AddGCPrologueCallback()
  66
  67 Signature:
  68
  69 ```c++
  70 void Nan::AddGCPrologueCallback(v8::Isolate::GCPrologueCallback, v8::GCType gc_type_filter callback)
  71 ```
  72
  73 Calls V8's [`AddGCPrologueCallback()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#ab4b87b8f9f8e5bf95eba4009357e001f).
  74
  75 <a name="api_nan_remove_gc_prologue_callback"></a>
  76 ### Nan::RemoveGCPrologueCallback()
  77
  78 Signature:
  79
  80 ```c++
  81 void Nan::RemoveGCPrologueCallback(v8::Isolate::GCPrologueCallback callback)
  82 ```
  83
  84 Calls V8's [`RemoveGCEpilogueCallback()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#a9f6c51932811593f81ff30b949124186).
  85
  86 <a name="api_nan_get_heap_statistics"></a>
  87 ### Nan::GetHeapStatistics()
  88
  89 Signature:
  90
  91 ```c++
  92 void Nan::GetHeapStatistics(v8::HeapStatistics *heap_statistics)
  93 ```
  94
  95 Calls V8's [`GetHeapStatistics()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#a5593ac74687b713095c38987e5950b34).
  96
  97 <a name="api_nan_set_counter_function"></a>
  98 ### Nan::SetCounterFunction()
  99
 100 Signature:
 101
 102 ```c++
 103 void Nan::SetCounterFunction(v8::CounterLookupCallback cb)
 104 ```
 105
 106 Calls V8's [`SetCounterFunction()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#a045d7754e62fa0ec72ae6c259b29af94).
 107
 108 <a name="api_nan_set_create_histogram_function"></a>
 109 ### Nan::SetCreateHistogramFunction()
 110
 111 Signature:
 112
 113 ```c++
 114 void Nan::SetCreateHistogramFunction(v8::CreateHistogramCallback cb)
 115 ```
 116
 117 Calls V8's [`SetCreateHistogramFunction()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#a542d67e85089cb3f92aadf032f99e732).
 118
 119 <a name="api_nan_set_add_histogram_sample_function"></a>
 120 ### Nan::SetAddHistogramSampleFunction()
 121
 122 Signature:
 123
 124 ```c++
 125 void Nan::SetAddHistogramSampleFunction(v8::AddHistogramSampleCallback cb)
 126 ```
 127
 128 Calls V8's [`SetAddHistogramSampleFunction()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#aeb420b690bc2c216882d6fdd00ddd3ea).
 129
 130 <a name="api_nan_idle_notification"></a>
 131 ### Nan::IdleNotification()
 132
 133 Signature:
 134
 135 ```c++
 136 void Nan::IdleNotification(v8::HeapStatistics *heap_statistics)
 137 ```
 138
 139 Calls V8's [`IdleNotification()` or `IdleNotificationDeadline()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#ad6a2a02657f5425ad460060652a5a118) depending on V8 version.
 140
 141 <a name="api_nan_low_memory_notification"></a>
 142 ### Nan::LowMemoryNotification()
 143
 144 Signature:
 145
 146 ```c++
 147 void Nan::LowMemoryNotification()
 148 ```
 149
 150 Calls V8's [`LowMemoryNotification()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#a24647f61d6b41f69668094bdcd6ea91f).
 151
 152 <a name="api_nan_context_disposed_notification"></a>
 153 ### Nan::ContextDisposedNotification()
 154
 155 Signature:
 156
 157 ```c++
 158 void Nan::ContextDisposedNotification()
 159 ```
 160
 161 Calls V8's [`ContextDisposedNotification()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#ad7f5dc559866343fe6cd8db1f134d48b).
 162
 163 <a name="api_nan_get_internal_field_pointer"></a>
 164 ### Nan::GetInternalFieldPointer()
 165
 166 Gets a pointer to the internal field with at `index` from a V8 `Object` handle.
 167
 168 Signature:
 169
 170 ```c++
 171 void* Nan::GetInternalFieldPointer(v8::Local<v8::Object> object, int index)
 172 ```
 173
 174 Calls the Object's [`GetAlignedPointerFromInternalField()` or `GetPointerFromInternalField()`](https://v8docs.nodesource.com/io.js-3.0/db/d85/classv8_1_1_object.html#ab3c57184263cf29963ef0017bec82281) depending on the version of V8.
 175
 176 <a name="api_nan_set_internal_field_pointer"></a>
 177 ### Nan::SetInternalFieldPointer()
 178
 179 Sets the value of the internal field at `index` on a V8 `Object` handle.
 180
 181 Signature:
 182
 183 ```c++
 184 void Nan::SetInternalFieldPointer(v8::Local<v8::Object> object, int index, void* value)
 185 ```
 186
 187 Calls the Object's [`SetAlignedPointerInInternalField()` or `SetPointerInInternalField()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#ad7f5dc559866343fe6cd8db1f134d48b) depending on the version of V8.
 188
 189 <a name="api_nan_adjust_external_memory"></a>
 190 ### Nan::AdjustExternalMemory()
 191
 192 Signature:
 193
 194 ```c++
 195 int Nan::AdjustExternalMemory(int bytesChange)
 196 ```
 197
 198 Calls V8's [`AdjustAmountOfExternalAllocatedMemory()`](https://v8docs.nodesource.com/io.js-3.0/d5/dda/classv8_1_1_isolate.html#ae1a59cac60409d3922582c4af675473e).
 199