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Instead, only reference count the SyntaxArena that the RawSyntax nodes live in. The user of RawSyntax nodes must guarantee that the SyntaxArena stays alive as long as the RawSyntax nodes are being accessed. During parse time, the SyntaxTreeCreator holds on to the SyntaxArena in which it creates RawSyntax nodes. When inspecting a syntax tree, the root SyntaxData node keeps the SyntaxArena alive. The change should be mostly invisible to the users of the public libSyntax API. This change significantly decreases the overall reference-counting overhead. Since we were not able to free individual RawSyntax nodes anyway, performing the reference-counting on the level of the SyntaxArena feels natural.
88 lines
3.2 KiB
C++
88 lines
3.2 KiB
C++
//===--- RawSyntaxTokenCache.cpp - Raw Token Cache --------------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#include "RawSyntaxTokenCache.h"
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#include "swift/Syntax/RawSyntax.h"
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#include "swift/Syntax/Trivia.h"
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#include "llvm/ADT/ArrayRef.h"
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using namespace swift;
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using namespace swift::syntax;
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static bool shouldCacheNode(tok TokKind, size_t TextSize,
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StringRef LeadingTrivia, StringRef TrailingTrivia) {
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// Is string_literal with >16 length.
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if (TokKind == tok::string_literal && TextSize > 16) {
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return false;
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}
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// Has a lot of leading comment trivia like comments.
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if (LeadingTrivia.size() > 4) {
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return false;
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}
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// Has a lot of trailing trivia
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if (TrailingTrivia.size() > 4) {
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return false;
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}
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// We can cache the node
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return true;
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}
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const RawSyntax *RawSyntaxTokenCache::getToken(RC<SyntaxArena> &Arena,
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tok TokKind, size_t TextLength,
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StringRef Text,
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StringRef LeadingTrivia,
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StringRef TrailingTrivia) {
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// Determine whether this token is worth to cache.
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if (!shouldCacheNode(TokKind, Text.size(), LeadingTrivia, TrailingTrivia)) {
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// Do not use cache.
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return RawSyntax::make(TokKind, Text, TextLength, LeadingTrivia,
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TrailingTrivia, SourcePresence::Present, Arena);
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}
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// This node is cacheable. Get or create.
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llvm::FoldingSetNodeID ID;
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RawSyntax::Profile(ID, TokKind, Text.str(), LeadingTrivia, TrailingTrivia);
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void *insertPos = nullptr;
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if (auto existing = CachedTokens.FindNodeOrInsertPos(ID, insertPos)) {
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// Found in the cache. Just return it.
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return existing->get();
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}
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// Could not found in the cache. Create it.
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auto Raw = RawSyntax::make(TokKind, Text, TextLength, LeadingTrivia,
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TrailingTrivia, SourcePresence::Present, Arena);
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auto IDRef = ID.Intern(Arena->getAllocator());
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auto CacheNode = new (Arena) RawSyntaxCacheNode(Raw, IDRef);
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// Keep track of the created RawSyntaxCacheNode so that we can destruct it
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// later.
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CacheNodes.push_back(CacheNode);
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CachedTokens.InsertNode(CacheNode, insertPos);
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return Raw;
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}
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RawSyntaxTokenCache::~RawSyntaxTokenCache() {
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// The CachedTokens folding set is no longer used. It does not, however, clean
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// up the RawSyntaxCacheNodes we created for it and would keep a strong
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// reference to their RawSyntax nodes.
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// We thus need to manually destruct the RawSyntaxCacheNodes here.
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// After all RawSyntax nodes in the current arena are disposed of, the
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// RawSyntaxCacheNode will also be destroyed, as they are allocated in that
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// arena.
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for (RawSyntaxCacheNode *Node : CacheNodes) {
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Node->~RawSyntaxCacheNode();
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}
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}
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