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af1f5d62ee
Summary: This diff replaces `SqliteStatement` in `TreeOverlayStore` with the new `PersistendSqliteStatement`. Reviewed By: chadaustin Differential Revision: D26656314 fbshipit-source-id: dbbfeddd52d3be2a1b5d3b6121d3694c41841fd5
74 lines
2.5 KiB
C++
74 lines
2.5 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This software may be used and distributed according to the terms of the
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* GNU General Public License version 2.
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*/
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#pragma once
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#include "eden/fs/sqlite/SqliteStatement.h"
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namespace facebook::eden {
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/**
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* Wrapper around `SqliteStatement` to denote a cached `SqliteStatement` that is
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* used repeatedly. Using this type of statement to save the cost of
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* preparation. All cached `SqliteStatement` should be using this type to
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* prevent incorrect usage.
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*
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* All cached `PersistentSqliteStatement` must be destroyed before calling
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* `sqlite3_close` (i.e. destroying `SqliteDatabase`). Otherwise the connection
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* won't be closed, causing memory leak.
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*/
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class PersistentSqliteStatement {
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public:
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/** Prepare to execute the statement described by the `query` parameter */
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PersistentSqliteStatement(
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folly::Synchronized<sqlite3*>::LockedPtr& db,
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folly::StringPiece sql)
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: stmt_(db, sql) {}
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/**
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* Join together the arguments as a single query string and prepare a
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* statement to execute them.
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*
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* Note: the `first` and `second` parameters are present to avoid a
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* delegation cycle for the otherwise amgiguous case of a single parameter.
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* It is desirable to do this because it saves an extraneous heap allocation
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* in the cases where the query string is known at compile time.
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*/
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template <typename Arg1, typename Arg2, typename... Args>
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PersistentSqliteStatement(
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folly::Synchronized<sqlite3*>::LockedPtr& db,
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Arg1&& first,
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Arg2&& second,
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Args&&... args)
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: PersistentSqliteStatement(
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db,
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folly::to<std::string>(
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std::forward<Arg1>(first),
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std::forward<Arg2>(second),
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std::forward<Args>(args)...)) {}
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PersistentSqliteStatement(const PersistentSqliteStatement&) = delete;
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PersistentSqliteStatement& operator=(const PersistentSqliteStatement&) =
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delete;
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PersistentSqliteStatement(PersistentSqliteStatement&&) = default;
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PersistentSqliteStatement& operator=(PersistentSqliteStatement&&) = default;
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/**
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* Obtain the cached statement for usage. The caller must be holding the
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* database lock in order to use the prepared statement. This function will
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* also take care of resetting the state of the given statement.
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*/
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SqliteStatement& get(folly::Synchronized<sqlite3*>::LockedPtr&) & {
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stmt_.reset();
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return stmt_;
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}
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private:
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SqliteStatement stmt_;
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};
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} // namespace facebook::eden
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