blob: ee9ba654cd4abbe6c9814de55d5bfdfa816cefa6 [file] [log] [blame]
// 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.
#include <memory>
#include <string>
#include "base/callback.h"
#include "base/files/file_path.h"
#include "base/memory/ref_counted.h"
#include "base/sequenced_task_runner.h"
#include "base/time/time.h"
#include "chromeos/chromeos_export.h"
namespace chromeos {
namespace printing {
// 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> {
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::Callback<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,
scoped_refptr<base::SequencedTaskRunner> disk_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, const 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::Callback<void()>& cb) = 0;
// Hook for testing. Returns true if all outstanding cache operations
// are complete.
virtual bool Idle() const = 0;
friend class base::RefCounted<PpdCache>;
virtual ~PpdCache() {}
} // namespace printing
} // namespace chromeos