Add RTrace shadow memory and instrumentation (#1476)

BREAKING CHANGE: RTrace is now a class and the onrealloc callback has been split into onresize and onmove.

lib/rtrace/README.md

@@ -5,17 +5,34 @@ A tiny utility that records allocations, retains, releases and frees performed b
 Instructions
 ------------
 
-Compile your module that uses the full or half runtime with `-use ASC_RTRACE=1` and include an instance of this module as the import named `rtrace`.
+Compile your module that uses the full or half runtime with `-use ASC_RTRACE=1 --explicitStart` and include an instance of this module as the import named `rtrace`.
 
 ```js
-var rtr = rtrace(e => {
-  // handle error
+var rtrace = new Rtrace({
+  onerror(err, info) {
+    // handle error
+  },
+  oninfo(msg) {
+    // print message, optional
+  },
+  getMemory() {
+    // obtain the module's memory,
+    // e.g. with --explicitStart:
+    return instance.exports.memory;
+  }
 });
 
-WebAssembly.instantiate(..., { rtrace: rtr, ... });
+var { module, instance } = await WebAssembly.instantiate(..., {
+  rtrace,
+  env: Object.assign({ //
+    ...                // only required when instrumenting memory
+  }, rtrace.env),      //
+  ...
+});
+instance.exports._start();
 ...
 
-if (rtr.active) {
+if (rtrace.active) {
   let leakCount = rtr.check();
   if (leakCount) {
     // handle error

lib/rtrace/index.d.ts

@@ -1,63 +1,41 @@
-/** Creates a new `RTrace` instance, tracking allocations, frees and reference counts. */
-declare function rtrace(
+/** Block information. */
+export declare interface BlockInfo {
+  /** Pointer to the block. */
+  ptr: number,
+  /** Block size. */
+  size: number,
+  /** Runtime header. */
+  header: {
+    /** Memory manager info bits. */
+    mmInfo: number,
+    /** Garbage collector info bits. */
+    gcInfo: number,
+    /** Runtime id. */
+    rtId: number,
+    /** Runtime size. */
+    rtSize: number
+  },
+  toString(): string
+}
+
+export declare interface RtraceOptions {
   /** Function being called when a problem is detected. */
-  onerror?: (error: Error) => void,
+  onerror?: (error: Error, info: BlockInfo) => void,
   /** Function being called with information messages. */
-  oninfo?: (info: string) => void
-): rtrace.RTrace;
-
-declare namespace rtrace {
-  /** The rtrace instance used as the `rtrace` import to the Wasm module. */
-  export interface RTrace {
-    /** Number of allocations so far. */
-    allocCount: number;
-    /** Number of reallocations so far. */
-    reallocCount: number;
-    /** Number of frees so far. */
-    freeCount: number;
-    /** Number of RC increments (retains) so far. */
-    incrementCount: number;
-    /** Number of RC decrements (releases) so far. */
-    decrementCount: number;
-
-    /** Called when a new block is allocated. */
-    onalloc(
-      /** New block being allocated. */
-      block: number
-    ): void;
-
-    /** Called when a block is reallocated and must be moved. */
-    onrealloc(
-      /** Block being moved. */
-      oldBlock: number,
-      /** New block used from now on. */
-      newBlock: number
-    ): void;
-
-    /** Called when a block is freed, implicitly or explicitly. */
-    onfree(
-      /** Block being freed. */
-      block: number
-    ): void;
+  oninfo?: (msg: string) => void,
+  /** Obtains the module's memory instance. */
+  getMemory()
+}
 
-    /** Called when a reference to a block is retained (RC incremented by one). */
-    onincrement(
-      /** Block a reference to is being retained. */
-      block: number
-    ): void;
+export declare class Rtrace {
+  [key: string]: unknown; // can be used as a Wasm import
 
-    /** Called when a reference to a block is released (RC decremented by one). */
-    ondecrement(
-      /** Block a reference to is being released. */
-      block: number
-    ): void;
+  /** Creates a new `RTrace` instance. */
+  constructor(options: RtraceOptions);
 
-    /** Checks if rtrace is active, i.e. at least one event has occurred. */
-    readonly active: boolean;
+  /** Checks if rtrace is active, i.e. at least one event has occurred. */
+  readonly active: boolean;
 
-    /** Checks if there are any leaks and emits them via `oninfo`. Returns the number of live blocks. */
-    check(): number;
-  }
+  /** Checks if there are any leaks and emits them via `oninfo`. Returns the number of live blocks. */
+  check(): number;
 }
-
-export = rtrace;