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dom/webidl/DominatorTree.webidl

author | Gregory Szorc <gps@mozilla.com> |

Fri, 22 Apr 2016 12:51:23 -0700 | |

changeset 294591 | d6ea7c8e2449d9b34882650490383ee86b8bb164 |

parent 274829 | a28821163fff5d0db7a5015e0eeb891b30bb38b7 |

child 406904 | 493e45400842b6ccfffb63b58b40b33a0b8154ab |

permissions | -rw-r--r-- |

Bug 1259782 - Build with Visual Studio 2015 Update 2; r=ted
Should be a drop-in replacement for VS2015u1.
MozReview-Commit-ID: HSmdikYPR0j

/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this file, * You can obtain one at http://mozilla.org/MPL/2.0/. */ typedef unsigned long long NodeId; typedef unsigned long long NodeSize; /** * In a directed graph with a root node `R`, a node `A` is said to "dominate" a * node `B` iff every path from `R` to `B` contains `A`. A node `A` is said to * be the "immediate dominator" of a node `B` iff it dominates `B`, is not `B` * itself, and does not dominate any other nodes which also dominate `B` in * turn. * * If we take every node from a graph `G` and create a new graph `T` with edges * to each node from its immediate dominator, then `T` is a tree (each node has * only one immediate dominator, or none if it is the root). This tree is called * a "dominator tree". * * This interface represents a dominator tree constructed from a HeapSnapshot's * heap graph. The domination relationship and dominator trees are useful tools * for analyzing heap graphs because they tell you: * * - Exactly what could be reclaimed by the GC if some node `A` became * unreachable: those nodes which are dominated by `A`, * * - The "retained size" of a node in the heap graph, in contrast to its * "shallow size". The "shallow size" is the space taken by a node itself, * not counting anything it references. The "retained size" of a node is its * shallow size plus the size of all the things that would be collected if * the original node wasn't (directly or indirectly) referencing them. In * other words, the retained size is the shallow size of a node plus the * shallow sizes of every other node it dominates. For example, the root * node in a binary tree might have a small shallow size that does not take * up much space itself, but it dominates the rest of the binary tree and * its retained size is therefore significant (assuming no external * references into the tree). */ [ChromeOnly, Exposed=(Window,System,Worker)] interface DominatorTree { /** * The `NodeId` for the root of the dominator tree. This is a "meta-root" in * that it has an edge to each GC root in the heap snapshot this dominator * tree was created from. */ readonly attribute NodeId root; /** * Get the retained size of the node with the given id. If given an invalid * id, null is returned. Throws an error on OOM. */ [Throws] NodeSize? getRetainedSize(NodeId node); /** * Get the set of ids of nodes immediately dominated by the node with the * given id. The resulting array is sorted by greatest to least retained * size. If given an invalid id, null is returned. Throws an error on OOM. */ [Throws] sequence<NodeId>? getImmediatelyDominated(NodeId node); /** * Get the immediate dominator of the node with the given id. Returns null if * given an invalid id, or the id of the root node. */ NodeId? getImmediateDominator(NodeId node); };