File size: 1,841 Bytes
1ce325b
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
78
79
80
81
82
83
84
85
86
87
88
#ifndef UTIL_STREAM_IO_H
#define UTIL_STREAM_IO_H

#include "util/exception.hh"
#include "util/file.hh"

namespace util {
namespace stream {

class ChainPosition;

class ReadSizeException : public util::Exception {
  public:
    ReadSizeException() throw();
    ~ReadSizeException() throw();
};

class Read {
  public:
    explicit Read(int fd) : file_(fd) {}
    void Run(const ChainPosition &position); 
  private:
    int file_;
};

// Like read but uses pread so that the file can be accessed from multiple threads.  
class PRead {
  public:
    explicit PRead(int fd, bool take_own = false) : file_(fd), own_(take_own) {}
    void Run(const ChainPosition &position);
  private:
    int file_;
    bool own_;
};

class Write {
  public:
    explicit Write(int fd) : file_(fd) {}
    void Run(const ChainPosition &position);
  private:
    int file_;
};

// It's a common case that stuff is written and then recycled.  So rather than
// spawn another thread to Recycle, this combines the two roles.
class WriteAndRecycle {
  public:
    explicit WriteAndRecycle(int fd) : file_(fd) {}
    void Run(const ChainPosition &position);
  private:
    int file_;
};

class PWriteAndRecycle {
  public:
    explicit PWriteAndRecycle(int fd) : file_(fd) {}
    void Run(const ChainPosition &position);
  private:
    int file_;
};


// Reuse the same file over and over again to buffer output.  
class FileBuffer {
  public:
    explicit FileBuffer(int fd) : file_(fd) {}

    PWriteAndRecycle Sink() const {
      util::SeekOrThrow(file_.get(), 0);
      return PWriteAndRecycle(file_.get());
    }

    PRead Source() const {
      return PRead(file_.get());
    }

    uint64_t Size() const {
      return SizeOrThrow(file_.get());
    }

  private:
    scoped_fd file_;
};

} // namespace stream
} // namespace util
#endif // UTIL_STREAM_IO_H