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Added PruneForest class, which is forest of "prune trees" where a prune tree is
a location that can be pruned with a tree of descendants that must be excluded from the pruning. PiperOrigin-RevId: 280315131
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‎database/src/desktop/persistence/prune_forest.cc

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// Copyright 2019 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "database/src/desktop/persistence/prune_forest.h"
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#include <set>
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#include <string>
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#include "app/src/assert.h"
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#include "app/src/path.h"
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#include "database/src/desktop/core/tree.h"
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namespace firebase {
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namespace database {
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namespace internal {
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static const Tree<bool> kPruneTree(true); // NOLINT
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static const Tree<bool> kKeepTree(false); // NOLINT
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static bool KeepPredicate(bool prune) { return !prune; }
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static bool PrunePredicate(bool prune) { return prune; }
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PruneForestRef::PruneForestRef(PruneForest* prune_forest)
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: prune_forest_(prune_forest) {}
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bool PruneForestRef::operator==(const PruneForestRef& other) const {
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return (prune_forest_ == other.prune_forest_) ||
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(prune_forest_ != nullptr && other.prune_forest_ != nullptr &&
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*prune_forest_ == *other.prune_forest_);
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}
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bool PruneForestRef::PrunesAnything() const {
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return prune_forest_->ContainsMatchingValue(PrunePredicate);
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}
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bool PruneForestRef::ShouldPruneUnkeptDescendants(const Path& path) const {
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const bool* should_prune = prune_forest_->LeafMostValue(path);
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return should_prune != nullptr && *should_prune;
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}
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bool PruneForestRef::ShouldKeep(const Path& path) const {
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const bool* should_prune = prune_forest_->LeafMostValue(path);
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return should_prune != nullptr && !*should_prune;
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}
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bool PruneForestRef::AffectsPath(const Path& path) const {
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return prune_forest_->RootMostValue(path) != nullptr ||
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(prune_forest_->GetChild(path) &&
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!prune_forest_->GetChild(path)->IsEmpty());
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}
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PruneForestRef PruneForestRef::GetChild(const std::string& key) {
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return PruneForestRef(prune_forest_->GetOrMakeSubtree(Path(key)));
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}
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const PruneForestRef PruneForestRef::GetChild(const std::string& key) const {
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return PruneForestRef(prune_forest_->GetOrMakeSubtree(Path(key)));
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}
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PruneForestRef PruneForestRef::GetChild(const Path& path) {
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return PruneForestRef(prune_forest_->GetOrMakeSubtree(path));
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}
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const PruneForestRef PruneForestRef::GetChild(const Path& path) const {
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return PruneForestRef(prune_forest_->GetOrMakeSubtree(path));
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}
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void PruneForestRef::Prune(const Path& path) {
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FIREBASE_DEV_ASSERT_MESSAGE(
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prune_forest_->RootMostValueMatching(path, KeepPredicate) == nullptr,
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"Can't prune path that was kept previously!")
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if (prune_forest_->RootMostValueMatching(path, PrunePredicate) != nullptr) {
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// This path will already be pruned
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} else {
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*prune_forest_->GetOrMakeSubtree(path) = kPruneTree;
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}
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}
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void PruneForestRef::Keep(const Path& path) {
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if (prune_forest_->RootMostValueMatching(path, KeepPredicate) != nullptr) {
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// This path will already be kept
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} else {
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*prune_forest_->GetOrMakeSubtree(path) = kKeepTree;
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}
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}
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void PruneForestRef::KeepAll(const Path& path,
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const std::set<std::string>& children) {
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if (prune_forest_->RootMostValueMatching(path, KeepPredicate) != nullptr) {
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// This path will already be kept.
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} else {
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DoAll(path, children, kKeepTree);
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}
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}
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void PruneForestRef::PruneAll(const Path& path,
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const std::set<std::string>& children) {
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FIREBASE_DEV_ASSERT_MESSAGE(
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prune_forest_->RootMostValueMatching(path, KeepPredicate) == nullptr,
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"Can't prune path that was kept previously!");
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if (prune_forest_->RootMostValueMatching(path, PrunePredicate) != nullptr) {
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// This path will already be pruned.
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} else {
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DoAll(path, children, kPruneTree);
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}
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}
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void PruneForestRef::DoAll(const Path& path,
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const std::set<std::string>& children,
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const Tree<bool>& keep_or_prune_tree) {
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Tree<bool>* subtree = prune_forest_->GetChild(path);
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for (const std::string& directory : children) {
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*subtree->GetOrMakeSubtree(Path(directory)) = keep_or_prune_tree;
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}
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}
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} // namespace internal
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} // namespace database
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} // namespace firebase

‎database/src/desktop/persistence/prune_forest.h

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// Copyright 2019 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef FIREBASE_DATABASE_CLIENT_CPP_SRC_DESKTOP_PERSISTENCE_PRUNE_FOREST_H_
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#define FIREBASE_DATABASE_CLIENT_CPP_SRC_DESKTOP_PERSISTENCE_PRUNE_FOREST_H_
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#include <set>
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#include <string>
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#include "app/src/path.h"
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#include "database/src/desktop/core/tree.h"
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namespace firebase {
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namespace database {
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namespace internal {
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// Forest of "prune trees" where a prune tree is a location that can be pruned
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// with a tree of descendants that must be excluded from the pruning.
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//
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// Internally we store this as a single tree of bools with the following
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// characteristics:
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//
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// * 'true' indicates a location that can be pruned, possibly
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// with some excluded descendants.
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// * 'false' indicates a location that we should keep (i.e. exclude from
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// pruning).
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// * 'true' (prune) cannot be a descendant of 'false' (keep). This will
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// trigger an exception.
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// * 'true' cannot be a descendant of 'true' (we'll just keep the more shallow
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// 'true').
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// * 'false' cannot be a descendant of 'false' (we'll just keep the more
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// shallow 'false').
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//
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typedef Tree<bool> PruneForest;
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// A PruneTreeRef is a way to operate on a PruneTree, treating any node as the
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// root. It provides fucntions to set or keep various locations, as well as
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// GetChild allow you to drill into the children of a location in the tree.
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// PruneForestRef is a lightweight object that does not take ownership of the
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// PruneForest passed to it.
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class PruneForestRef {
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public:
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explicit PruneForestRef(PruneForest* prune_forest);
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// Check if this PruneForestRef is equal to another PruneForestRef. This is
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// mostly used for testing.
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bool operator==(const PruneForestRef& other) const;
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// Check if this PruneForestRef is not equal to another PruneForestRef. This
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// is mostly used for testing.
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bool operator!=(const PruneForestRef& other) const {
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return !(*this == other);
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}
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// Returns true if this PruneForestRef prunes anything.
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bool PrunesAnything() const;
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// Indicates that path is marked for pruning, so anything below it that didn't
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// have keep() called on it should be pruned.
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//
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// @param path The path in question
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// @return True if we should prune descendants that didn't have keep() called
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// on them.
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bool ShouldPruneUnkeptDescendants(const Path& path) const;
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// Returns true if the given path should be kept.
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bool ShouldKeep(const Path& path) const;
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// Returns true if the given path should be pruned.
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bool AffectsPath(const Path& path) const;
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// Get the child of this tree at the given key.
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PruneForestRef GetChild(const std::string& key);
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const PruneForestRef GetChild(const std::string& key) const;
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// Get the child of this tree at the given path.
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PruneForestRef GetChild(const Path& path);
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const PruneForestRef GetChild(const Path& path) const;
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// Mark that the value at the given path should be pruned.
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void Prune(const Path& path);
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// Mark that the value at the given path should be kept.
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void Keep(const Path& path);
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// Mark that the given child values at the given path should be kept.
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void KeepAll(const Path& path, const std::set<std::string>& children);
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// Mark that the given child values at the given path should be pruned.
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void PruneAll(const Path& path, const std::set<std::string>& children);
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// Accumulate a result given a visitor function to be applied to all nodes
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// that are marked as being kept.
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template <typename T, typename Func>
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T FoldKeptNodes(const T& start_value, const Func& visitor) const {
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return prune_forest_->Fold(
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start_value,
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[visitor](const Path& relative_path, bool prune, const T& accum) -> T {
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if (!prune) {
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return visitor(relative_path, nullptr, accum);
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} else {
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return accum;
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}
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});
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}
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private:
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void DoAll(const Path& path, const std::set<std::string>& children,
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const Tree<bool>& keep_or_prune_tree);
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PruneForest* prune_forest_;
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};
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} // namespace internal
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} // namespace database
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} // namespace firebase
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#endif // FIREBASE_DATABASE_CLIENT_CPP_SRC_DESKTOP_PERSISTENCE_PRUNE_FOREST_H_

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