| // 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/files/file_path.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/time/time.h" |
| #include "chromeos/chromeos_export.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. |
| // |
| // All cache functions must be called on a thread which is permitted to do I/O. |
| class CHROMEOS_EXPORT 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? |
| base::TimeDelta age; |
| |
| // Contents of the entry. |
| 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); |
| |
| // 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 the given contents at the given key. If cb is non-null, it will |
| // be invoked on completion. |
| virtual void Store(const std::string& key, |
| const std::string& contents, |
| const base::Closure& cb) = 0; |
| |
| protected: |
| friend class base::RefCounted<PpdCache>; |
| virtual ~PpdCache() {} |
| }; |
| |
| } // namespace chromeos |
| |
| #endif // CHROMEOS_PRINTING_PPD_CACHE_H_ |