1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
|
// Copyright 2016 The Chromium Authors
// 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/component_export.h"
#include "base/files/file_path.h"
#include "base/functional/callback.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_
|
