Implementing break on load

src/chrome/breakOnLoadHelper.ts

@@ -0,0 +1,238 @@
+/*---------------------------------------------------------
+ * Copyright (C) Microsoft Corporation. All rights reserved.
+ *--------------------------------------------------------*/
+
+import {logger} from 'vscode-debugadapter';
+import {ISetBreakpointResult, BreakOnLoadStrategy} from '../debugAdapterInterfaces';
+
+import Crdp from '../../crdp/crdp';
+import {ChromeDebugAdapter} from './chromeDebugAdapter';
+import * as ChromeUtils from './chromeUtils';
+
+export class BreakOnLoadHelper {
+
+    public userBreakpointOnLine1Col1: boolean = false;
+    private _instrumentationBreakpointSet: boolean = false;
+
+    // Break on load: Store some mapping between the requested file names, the regex for the file, and the chrome breakpoint id to perform lookup operations efficiently
+    private _stopOnEntryBreakpointIdToRequestedFileName = new Map<string, [string, Set<string>]>();
+    private _stopOnEntryRequestedFileNameToBreakpointId = new Map<string, string>();
+    private _stopOnEntryRegexToBreakpointId = new Map<string, string>();
+
+    private _chromeDebugAdapter: ChromeDebugAdapter;
+    private _breakOnLoadStrategy: BreakOnLoadStrategy;
+
+    public constructor(chromeDebugAdapter: ChromeDebugAdapter, breakOnLoadStrategy: BreakOnLoadStrategy) {
+        this._chromeDebugAdapter = chromeDebugAdapter;
+        this._breakOnLoadStrategy = breakOnLoadStrategy;
+    }
+
+    public get stopOnEntryRequestedFileNameToBreakpointId(): Map<string, string> {
+        return this._stopOnEntryRequestedFileNameToBreakpointId;
+    }
+
+    public get stopOnEntryBreakpointIdToRequestedFileName(): Map<string, [string, Set<string>]> {
+        return this._stopOnEntryBreakpointIdToRequestedFileName;
+    }
+
+    private get instrumentationBreakpointSet(): boolean {
+        return this._instrumentationBreakpointSet;
+    }
+
+    /**
+     * Checks and resolves the pending breakpoints of a script. If any breakpoints were resolved returns true, else false.
+     * Used when break on load active, either through Chrome's Instrumentation Breakpoint API or the regex approach
+     */
+    private async resolvePendingBreakpointsOfPausedScript(scriptId: string): Promise<boolean> {
+        const pausedScriptUrl = this._chromeDebugAdapter.scriptsById.get(scriptId).url;
+        const mappedUrl = await this._chromeDebugAdapter.pathTransformer.scriptParsed(pausedScriptUrl);
+
+        const pendingBreakpoints = this._chromeDebugAdapter.pendingBreakpointsByUrl.get(mappedUrl);
+        // If the file has unbound breakpoints, resolve them and return true
+        if (pendingBreakpoints !== undefined) {
+            await this._chromeDebugAdapter.resolvePendingBreakpoint(pendingBreakpoints);
+            return true;
+        } else {
+            // If no pending breakpoints, return false
+            return false;
+        }
+    }
+
+    /**
+     * Handles the onpaused event.
+     * Checks if the event is caused by a stopOnEntry breakpoint of using the regex approach, or the paused event due to the Chrome's instrument approach
+     * Returns whether we should continue or not on this paused event
+     */
+    public async handleOnPaused(notification: Crdp.Debugger.PausedEvent): Promise<boolean> {
+        if (notification.hitBreakpoints && notification.hitBreakpoints.length) {
+            // If breakOnLoadStrategy is set to regex, we may have hit a stopOnEntry breakpoint we put.
+            // So we need to resolve all the pending breakpoints in this script and then decide to continue or not
+            if (this._breakOnLoadStrategy === 'regex') {
+                let shouldContinue = await this.handleStopOnEntryBreakpointAndContinue(notification);
+                return shouldContinue;
+            }
+        } else if (notification.reason === 'EventListener' && notification.data.eventName === "instrumentation:scriptFirstStatement" ) {
+            // This is fired when Chrome stops on the first line of a script when using the setInstrumentationBreakpoint API
+
+            const pausedScriptId = notification.callFrames[0].location.scriptId;
+            // Now we should resolve all the pending breakpoints and then continue
+            await this.resolvePendingBreakpointsOfPausedScript(pausedScriptId);
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * Returns whether we should continue on hitting a stopOnEntry breakpoint
+     * Only used when using regex approach for break on load
+     */
+    private async shouldContinueOnStopOnEntryBreakpoint(scriptId: string): Promise<boolean> {
+        // If the file has no unbound breakpoints or none of the resolved breakpoints are at (1,1), we should continue after hitting the stopOnEntry breakpoint
+        let shouldContinue = true;
+        let anyPendingBreakpointsResolved = await this.resolvePendingBreakpointsOfPausedScript(scriptId);
+
+        // If there were any pending breakpoints resolved and any of them was at (1,1) we shouldn't continue
+        if (anyPendingBreakpointsResolved && this.userBreakpointOnLine1Col1) {
+            // Here we need to store this information per file, but since we can safely assume that scriptParsed would immediately be followed by onPaused event
+            // for the breakonload files, this implementation should be fine
+            this.userBreakpointOnLine1Col1 = false;
+            shouldContinue = false;
+        }
+
+        return shouldContinue;
+    }
+
+    /**
+     * Handles a script with a stop on entry breakpoint and returns whether we should continue or not on hitting that breakpoint
+     * Only used when using regex approach for break on load
+     */
+    private async handleStopOnEntryBreakpointAndContinue(notification: Crdp.Debugger.PausedEvent): Promise<boolean> {
+        const hitBreakpoints = notification.hitBreakpoints;
+        let allStopOnEntryBreakpoints = true;
+
+        // If there is a breakpoint which is not a stopOnEntry breakpoint, we appear as if we hit that one
+        // This is particularly done for cases when we end up with a user breakpoint and a stopOnEntry breakpoint on the same line
+        hitBreakpoints.forEach(bp => {
+            if (!this._stopOnEntryBreakpointIdToRequestedFileName.has(bp)) {
+                notification.hitBreakpoints = [bp];
+                allStopOnEntryBreakpoints = false;
+            }
+        });
+
+        // If all the breakpoints on this point are stopOnEntry breakpoints
+        // This will be true in cases where it's a single breakpoint and it's a stopOnEntry breakpoint
+        // This can also be true when we have multiple breakpoints and all of them are stopOnEntry breakpoints, for example in cases like index.js and index.bin.js
+        // Suppose user puts breakpoints in both index.js and index.bin.js files, when the setBreakpoints function is called for index.js it will set a stopOnEntry
+        // breakpoint on index.* files which will also match index.bin.js. Now when setBreakpoints is called for index.bin.js it will again put a stopOnEntry breakpoint
+        // in itself. So when the file is actually loaded, we would have 2 stopOnEntry breakpoints */
+
+        if (allStopOnEntryBreakpoints) {
+            const pausedScriptId = notification.callFrames[0].location.scriptId;
+            let shouldContinue = await this.shouldContinueOnStopOnEntryBreakpoint(pausedScriptId);
+            if (shouldContinue) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Adds a stopOnEntry breakpoint for the given script url
+     * Only used when using regex approach for break on load
+     */
+    private async addStopOnEntryBreakpoint(url: string): Promise<ISetBreakpointResult[]> {
+        let responsePs: ISetBreakpointResult[];
+        // Check if file already has a stop on entry breakpoint
+        if (!this._stopOnEntryRequestedFileNameToBreakpointId.has(url)) {
+
+            // Generate regex we need for the file
+            const urlRegex = ChromeUtils.getUrlRegexForBreakOnLoad(url);
+
+            // Check if we already have a breakpoint for this regexp since two different files like script.ts and script.js may have the same regexp
+            let breakpointId: string;
+            breakpointId = this._stopOnEntryRegexToBreakpointId.get(urlRegex);
+
+            // If breakpointId is undefined it means the breakpoint doesn't exist yet so we add it
+            if (breakpointId === undefined) {
+                let result;
+                try {
+                    result = await this.setStopOnEntryBreakpoint(urlRegex);
+                } catch (e) {
+                    logger.log(`Exception occured while trying to set stop on entry breakpoint ${e.message}.`);
+                }
+                if (result) {
+                    breakpointId = result.breakpointId;
+                    this._stopOnEntryRegexToBreakpointId.set(urlRegex, breakpointId);
+                } else {
+                    logger.log(`BreakpointId was null when trying to set on urlregex ${urlRegex}. This normally happens if the breakpoint already exists.`);
+                }
+                responsePs = [result];
+            } else {
+                responsePs = [];
+            }
+
+            // Store the new breakpointId and the file name in the right mappings
+            this._stopOnEntryRequestedFileNameToBreakpointId.set(url, breakpointId);
+
+            let regexAndFileNames = this._stopOnEntryBreakpointIdToRequestedFileName.get(breakpointId);
+
+            // If there already exists an entry for the breakpoint Id, we add this file to the list of file mappings
+            if (regexAndFileNames !== undefined) {
+                regexAndFileNames[1].add(url);
+            } else { // else create an entry for this breakpoint id
+                const fileSet = new Set<string>();
+                fileSet.add(url);
+                this._stopOnEntryBreakpointIdToRequestedFileName.set(breakpointId, [urlRegex, fileSet]);
+            }
+        } else {
+            responsePs = [];
+        }
+        return Promise.all(responsePs);
+    }
+
+    /**
+     * Handles the AddBreakpoints request when break on load is active
+     * Takes the action based on the strategy
+     */
+    public async handleAddBreakpoints(url: string): Promise<ISetBreakpointResult[]> {
+        // If the strategy is set to regex, we try to match the file where user put the breakpoint through a regex and tell Chrome to put a stop on entry breakpoint there
+        if (this._breakOnLoadStrategy === 'regex') {
+            return this.addStopOnEntryBreakpoint(url);
+        } else if (this._breakOnLoadStrategy === 'instrument') {
+            // Else if strategy is to use Chrome's experimental instrumentation API, we stop on all the scripts at the first statement before execution
+            if (!this.instrumentationBreakpointSet) {
+                await this.setInstrumentationBreakpoint();
+            }
+            return [];
+        }
+        return undefined;
+    }
+
+    /**
+     * Tells Chrome to set instrumentation breakpoint to stop on all the scripts before execution
+     * Only used when using instrument approach for break on load
+     */
+    private async setInstrumentationBreakpoint(): Promise<void> {
+        this._chromeDebugAdapter.chrome.DOMDebugger.setInstrumentationBreakpoint({eventName: "scriptFirstStatement"});
+        this._instrumentationBreakpointSet = true;
+    }
+
+    // Sets a breakpoint on (0,0) for the files matching the given regex
+    private async setStopOnEntryBreakpoint(urlRegex: string): Promise<Crdp.Debugger.SetBreakpointByUrlResponse> {
+        let result = await this._chromeDebugAdapter.chrome.Debugger.setBreakpointByUrl({ urlRegex, lineNumber: 0, columnNumber: 0 });
+        return result;
+    }
+
+    /**
+     * Checks if we need to call resolvePendingBPs on scriptParsed event
+     * If break on load is active and we are using the regex approach, only call the resolvePendingBreakpoint function for files where we do not
+     * set break on load breakpoints. For those files, it is called from onPaused function.
+     * For the default Chrome's API approach, we don't need to call resolvePendingBPs from inside scriptParsed
+     */
+    public shouldResolvePendingBPs(mappedUrl: string): boolean {
+        if (this._breakOnLoadStrategy === 'regex' && !this.stopOnEntryRequestedFileNameToBreakpointId.has(mappedUrl)) {
+            return true;
+        }
+        return false;
+    }
+}