From 2ec69955556bf92f49355659b6126e08fa2c3298 Mon Sep 17 00:00:00 2001
From: James M Snell <jasnell@gmail.com>
Date: Fri, 23 Mar 2018 11:23:22 -0700
Subject: perf_hooks: simplify perf_hooks

Remove the `performance.getEntries()` and `performance.clear*()`
variants and eliminate the accumulation of the global timeline
entries. The design of this particular bit of the API is a memory
leak and performance footgun. The `PerformanceObserver` API is
a better approach to consuming the data in a more transient way.

PR-URL: https://github.com/nodejs/node/pull/19563
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
---
 lib/perf_hooks.js | 101 ++++--------------------------------------------------
 1 file changed, 7 insertions(+), 94 deletions(-)

(limited to 'lib/perf_hooks.js')

diff --git a/lib/perf_hooks.js b/lib/perf_hooks.js
index 7fa5501b28..9080cc7f26 100644
--- a/lib/perf_hooks.js
+++ b/lib/perf_hooks.js
@@ -3,6 +3,7 @@
 const {
   PerformanceEntry,
   mark: _mark,
+  clearMark: _clearMark,
   measure: _measure,
   milestones,
   observerCounts,
@@ -50,17 +51,11 @@ const kBuffering = Symbol('buffering');
 const kQueued = Symbol('queued');
 const kTimerified = Symbol('timerified');
 const kInsertEntry = Symbol('insert-entry');
-const kIndexEntry = Symbol('index-entry');
-const kClearEntry = Symbol('clear-entry');
 const kGetEntries = Symbol('get-entries');
 const kIndex = Symbol('index');
 const kMarks = Symbol('marks');
 const kCount = Symbol('count');
-const kMaxCount = Symbol('max-count');
-const kDefaultMaxCount = 150;
 
-observerCounts[NODE_PERFORMANCE_ENTRY_TYPE_MARK] = 1;
-observerCounts[NODE_PERFORMANCE_ENTRY_TYPE_MEASURE] = 1;
 const observers = {};
 const observerableTypes = [
   'node',
@@ -286,17 +281,12 @@ class PerformanceObserverEntryList {
     const item = { entry };
     L.append(this[kEntries], item);
     this[kCount]++;
-    this[kIndexEntry](item);
   }
 
   get length() {
     return this[kCount];
   }
 
-  [kIndexEntry](entry) {
-    // Default implementation does nothing
-  }
-
   [kGetEntries](name, type) {
     const ret = [];
     const list = this[kEntries];
@@ -407,72 +397,11 @@ class PerformanceObserver extends AsyncResource {
   }
 }
 
-class Performance extends PerformanceObserverEntryList {
+class Performance {
   constructor() {
-    super();
     this[kIndex] = {
       [kMarks]: new Set()
     };
-    this[kMaxCount] = kDefaultMaxCount;
-    this[kInsertEntry](nodeTiming);
-  }
-
-  set maxEntries(val) {
-    if (typeof val !== 'number' || val >>> 0 !== val) {
-      const errors = lazyErrors();
-      throw new errors.ERR_INVALID_ARG_TYPE('val', 'number', val);
-    }
-    this[kMaxCount] = Math.max(1, val >>> 0);
-  }
-
-  get maxEntries() {
-    return this[kMaxCount];
-  }
-
-  [kIndexEntry](item) {
-    const index = this[kIndex];
-    const type = item.entry.entryType;
-    let items = index[type];
-    if (!items) {
-      items = index[type] = {};
-      L.init(items);
-    }
-    const entry = item.entry;
-    L.append(items, { entry, item });
-    const count = this[kCount];
-    if (count > this[kMaxCount]) {
-      const text = count === 1 ? 'is 1 entry' : `are ${count} entries`;
-      process.emitWarning('Possible perf_hooks memory leak detected. ' +
-                          `There ${text} in the ` +
-                          'Performance Timeline. Use the clear methods ' +
-                          'to remove entries that are no longer needed or ' +
-                          'set performance.maxEntries equal to a higher ' +
-                          'value (currently the maxEntries is ' +
-                          `${this[kMaxCount]}).`);
-    }
-  }
-
-  [kClearEntry](type, name) {
-    const index = this[kIndex];
-    const items = index[type];
-    if (!items) return;
-    let item = L.peek(items);
-    while (item && item !== items) {
-      const entry = item.entry;
-      const next = item._idlePrev;
-      if (name !== undefined) {
-        if (entry.name === `${name}`) {
-          L.remove(item); // remove from the index
-          L.remove(item.item); // remove from the master
-          this[kCount]--;
-        }
-      } else {
-        L.remove(item); // remove from the index
-        L.remove(item.item); // remove from the master
-        this[kCount]--;
-      }
-      item = next;
-    }
   }
 
   get nodeTiming() {
@@ -507,27 +436,13 @@ class Performance extends PerformanceObserverEntryList {
 
   clearMarks(name) {
     name = name !== undefined ? `${name}` : name;
-    this[kClearEntry]('mark', name);
-    if (name !== undefined)
+    if (name !== undefined) {
       this[kIndex][kMarks].delete(name);
-    else
+      _clearMark(name);
+    } else {
       this[kIndex][kMarks].clear();
-  }
-
-  clearMeasures(name) {
-    this[kClearEntry]('measure', name);
-  }
-
-  clearGC() {
-    this[kClearEntry]('gc');
-  }
-
-  clearFunctions(name) {
-    this[kClearEntry]('function', name);
-  }
-
-  clearEntries(name) {
-    this[kClearEntry](name);
+      _clearMark();
+    }
   }
 
   timerify(fn) {
@@ -563,7 +478,6 @@ class Performance extends PerformanceObserverEntryList {
 
   [kInspect]() {
     return {
-      maxEntries: this.maxEntries,
       nodeTiming: this.nodeTiming,
       timeOrigin: this.timeOrigin
     };
@@ -595,7 +509,6 @@ function observersCallback(entry) {
   if (type === NODE_PERFORMANCE_ENTRY_TYPE_HTTP2)
     collectHttp2Stats(entry);
 
-  performance[kInsertEntry](entry);
   const list = getObserversList(type);
 
   let current = L.peek(list);
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