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- // Copyright 2016 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #ifndef CHROMEOS_PRINTING_PPD_CACHE_H_
- #define CHROMEOS_PRINTING_PPD_CACHE_H_
- #include <memory>
- #include <string>
- #include "base/callback.h"
- #include "base/component_export.h"
- #include "base/files/file_path.h"
- #include "base/memory/ref_counted.h"
- #include "base/task/sequenced_task_runner.h"
- #include "base/time/time.h"
- namespace chromeos {
- // PpdCache manages a cache of locally-stored PPD files. At its core, it
- // operates like a persistent hash from PpdReference to files. If you give the
- // same PpdReference to Find() that was previously given to store, you should
- // get the same FilePath back out (unless the previous entry has timed out of
- // the cache). However, changing *any* field in PpdReference will make the
- // previous cache entry invalid. This is the intentional behavior -- we want to
- // re-run the resolution logic if we have new meta-information about a printer.
- class COMPONENT_EXPORT(CHROMEOS_PRINTING) PpdCache
- : public base::RefCounted<PpdCache> {
- public:
- struct FindResult {
- // Did we find something? If this is false, none of the other fields are
- // valid.
- bool success = false;
- // How old is this entry? Zero on failure.
- base::TimeDelta age;
- // Contents of the entry. Empty on failure.
- std::string contents;
- };
- using FindCallback = base::OnceCallback<void(const FindResult& result)>;
- // Create and return a Ppdcache that uses cache_dir to store state. If
- // cache_base_dir does not exist, it will be lazily created the first time the
- // cache needs to store state.
- static scoped_refptr<PpdCache> Create(const base::FilePath& cache_base_dir);
- // Create a PpdCache that uses the given task runner for background
- // processing.
- static scoped_refptr<PpdCache> CreateForTesting(
- const base::FilePath& cache_base_dir,
- scoped_refptr<base::SequencedTaskRunner> io_task_runner);
- // Start a Find, looking, for an entry with the given key that is at most
- // |max_age| old. |cb| will be invoked on the calling thread.
- virtual void Find(const std::string& key, FindCallback cb) = 0;
- // Store |contents| at the the location indicated by |key|. The
- // file operation will complete asynchronously.
- virtual void Store(const std::string& key,
- const std::string& contents) = 0;
- // Store the given contents at the given key, and change the resulting
- // cache file's last modified date to be |age| before now.
- virtual void StoreForTesting(const std::string& key,
- const std::string& contents,
- base::TimeDelta age) = 0;
- protected:
- friend class base::RefCounted<PpdCache>;
- virtual ~PpdCache() {}
- };
- } // namespace chromeos
- #endif // CHROMEOS_PRINTING_PPD_CACHE_H_
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