/*
* Copyright 2008 The Closure Compiler Authors.
*
* 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.
*/
package com.google.javascript.jscomp;
import com.google.common.collect.ImmutableList;
import com.google.javascript.jscomp.ControlFlowGraph.Branch;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.jscomp.graph.DiGraph.DiGraphNode;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;
import java.util.List;
/**
* Instruments functions for when functions first get called and defined.
*
* This pass be used to instrument code to:
* 1. Gather statistics from real users in the wild.
* 2. Incorporate utilization statistics into Selenium tests
* 3. Access utilization statistics from an app's debug UI
*
* By parametrizing the whole instrumentation process we expect to be
* able to support a wide variety of use cases and minimize the cost
* of developing new instrumentation schemes.
*
* TODO(user): This pass currently runs just before the variable and
* property renaming near the end of the optimization pass. I think
* Mark put it there to minimize the difference between the code
* generated with/without instrumentation; instrumentation makes
* several optimization passes do less, for example inline functions.
*
* My opinion is that we want utilization/profiling information for
* all function. This pass should run before most passes that modify
* the AST (exception being the localization pass, which makes
* assumptions about the structure of the AST). We should move the
* pass up, list inlined functions or give clients the option to
* instrument before or after optimization.
*
*/
class InstrumentFunctions implements CompilerPass {
private final AbstractCompiler compiler;
private final FunctionNames functionNames;
private final String appNameStr;
private final String initCodeSource;
private final String definedFunctionName;
private final String reportFunctionName;
private final String reportFunctionExitName;
private final String appNameSetter;
private final List<String> declarationsToRemove;
/**
* Creates an instrument functions compiler pass.
*
* @param compiler The JSCompiler
* @param functionNames Assigned function identifiers.
* @param template Instrumentation template; for use during error reporting only.
* @param appNameStr String to pass to appNameSetter.
*/
InstrumentFunctions(AbstractCompiler compiler,
FunctionNames functionNames,
Instrumentation template,
String appNameStr) {
this.compiler = compiler;
this.functionNames = functionNames;
this.appNameStr = appNameStr;
StringBuilder initCodeSourceBuilder = new StringBuilder();
for (String line : template.getInitList()) {
initCodeSourceBuilder.append(line).append("\n");
}
this.initCodeSource = initCodeSourceBuilder.toString();
this.definedFunctionName = template.getReportDefined();
this.reportFunctionName = template.getReportCall();
this.reportFunctionExitName = template.getReportExit();
this.appNameSetter = template.getAppNameSetter();
this.declarationsToRemove = ImmutableList.copyOf(
template.getDeclarationToRemoveList());
}
@Override
public void process(Node externs, Node root) {
Node initCode = null;
if (!initCodeSource.isEmpty()) {
Node initCodeRoot = compiler.parseSyntheticCode(
"template:init", initCodeSource);
if (initCodeRoot != null && initCodeRoot.getFirstChild() != null) {
NodeUtil.markNewScopesChanged(initCodeRoot, compiler);
initCode = initCodeRoot.removeChildren();
} else {
return; // parse failure
}
}
NodeTraversal.traverseEs6(compiler, root,
new RemoveCallback(declarationsToRemove));
NodeTraversal.traverseEs6(compiler, root, new InstrumentCallback());
if (!appNameSetter.isEmpty()) {
Node call = IR.call(
IR.name(appNameSetter),
IR.string(appNameStr));
call.putBooleanProp(Node.FREE_CALL, true);
Node expr = IR.exprResult(call);
Node addingRoot = compiler.getNodeForCodeInsertion(null);
addingRoot.addChildToFront(expr.useSourceInfoIfMissingFromForTree(addingRoot));
compiler.reportChangeToEnclosingScope(addingRoot);
}
if (initCode != null) {
Node addingRoot = compiler.getNodeForCodeInsertion(null);
addingRoot.addChildrenToFront(initCode);
compiler.reportChangeToEnclosingScope(addingRoot);
}
}
/**
* The application must refer to these variables to output them so the
* application must also declare these variables for the first
* {@link VarCheck} pass. These declarations must be removed before the
* second {@link VarCheck} pass. Otherwise, the second pass would warn about
* duplicate declarations.
*/
private static class RemoveCallback extends AbstractPostOrderCallback {
private final List<String> removable;
RemoveCallback(List<String> removable) {
this.removable = removable;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (NodeUtil.isVarDeclaration(n) && removable.contains(n.getString())) {
parent.removeChild(n);
if (!parent.hasChildren()) {
parent.detach();
}
}
}
}
/**
* Traverse a function's body by instrument return sites by
* inserting calls to {@code reportFunctionExitName}. If the
* function is missing an explicit return statement in some control
* path, this pass inserts a call to {@code reportFunctionExitName}
* as the last statement in the function's body.
*
* Example:
* Input:
* function f() {
* if (pred) {
* return a;
* }
* }
*
* Template:
* reportFunctionExitName: "onExitFn"
*
* Output:
* function f() {
* if (pred) {
* return onExitFn(0, a, "f");
* }
* onExitFn(0, undefined, "f");
* }
*
**/
private class InstrumentReturns implements NodeTraversal.Callback {
private final int functionId;
private final String functionName;
/**
* @param functionId Function identifier computed by FunctionNames;
* used as first argument to {@code reportFunctionExitName}
* {@code reportFunctionExitName} must be a 3 argument function that
* returns it's second argument.
* @param functionName Function name.
*/
InstrumentReturns(int functionId, String functionName) {
this.functionId = functionId;
this.functionName = functionName;
}
/**
* @param function function with id == this.functionId
*/
void process(Node function) {
Node body = function.getLastChild();
NodeTraversal.traverseEs6(compiler, body, this);
if (!allPathsReturn(function)) {
Node call = newReportFunctionExitNode(function, null);
Node expr = IR.exprResult(call).useSourceInfoIfMissingFromForTree(function);
body.addChildToBack(expr);
compiler.reportChangeToEnclosingScope(body);
}
}
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
return !n.isFunction();
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (!n.isReturn()) {
return;
}
Node returnRhs = n.removeFirstChild();
Node call = newReportFunctionExitNode(n, returnRhs);
n.addChildToFront(call);
t.reportCodeChange();
}
private Node newReportFunctionExitNode(Node infoNode, Node returnRhs) {
Node call = IR.call(
IR.name(reportFunctionExitName),
IR.number(functionId),
(returnRhs != null) ? returnRhs : IR.name("undefined"),
IR.string(functionName));
call.putBooleanProp(Node.FREE_CALL, true);
call.useSourceInfoFromForTree(infoNode);
return call;
}
/**
* @return true if all paths from block must exit with an explicit return.
*/
private boolean allPathsReturn(Node function) {
// Computes the control flow graph.
ControlFlowAnalysis cfa = new ControlFlowAnalysis(
compiler, false, false);
cfa.process(null, function);
ControlFlowGraph<Node> cfg = cfa.getCfg();
Node returnPathsParent = cfg.getImplicitReturn().getValue();
for (DiGraphNode<Node, Branch> pred :
cfg.getDirectedPredNodes(returnPathsParent)) {
Node n = pred.getValue();
if (!n.isReturn()) {
return false;
}
}
return true;
}
}
private class InstrumentCallback extends AbstractPostOrderCallback {
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (!n.isFunction()) {
return;
}
int id = functionNames.getFunctionId(n);
if (id < 0) {
// Function node was added during compilation; don't instrument.
return;
}
String name = functionNames.getFunctionName(n);
if (!reportFunctionName.isEmpty()) {
Node body = n.getLastChild();
Node call = IR.call(
IR.name(reportFunctionName),
IR.number(id),
IR.string(name),
IR.name("arguments"));
call.putBooleanProp(Node.FREE_CALL, true);
Node expr = IR.exprResult(call);
expr.useSourceInfoFromForTree(n);
body.addChildToFront(expr);
t.reportCodeChange();
}
if (!reportFunctionExitName.isEmpty()) {
(new InstrumentReturns(id, name)).process(n);
}
if (!definedFunctionName.isEmpty()) {
Node call = IR.call(
IR.name(definedFunctionName),
IR.number(id),
IR.string(name));
call.putBooleanProp(Node.FREE_CALL, true);
call.useSourceInfoFromForTree(n);
Node expr = NodeUtil.newExpr(call);
Node addingRoot = null;
if (NodeUtil.isFunctionDeclaration(n)) {
JSModule module = t.getModule();
addingRoot = compiler.getNodeForCodeInsertion(module);
addingRoot.addChildToFront(expr);
} else {
Node beforeChild = n;
for (Node ancestor : n.getAncestors()) {
Token type = ancestor.getToken();
if (type == Token.BLOCK || type == Token.SCRIPT) {
addingRoot = ancestor;
break;
}
beforeChild = ancestor;
}
addingRoot.addChildBefore(expr, beforeChild);
}
compiler.reportChangeToEnclosingScope(addingRoot);
}
}
}
}