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
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
//===- FileSystemStatCache.cpp - Caching for 'stat' calls -----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the FileSystemStatCache interface.
//
//===----------------------------------------------------------------------===//
#include "clang/Basic/FileSystemStatCache.h"
#include "llvm/Support/Chrono.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/VirtualFileSystem.h"
#include <utility>
using namespace clang;
void FileSystemStatCache::anchor() {}
static void copyStatusToFileData(const llvm::vfs::Status &Status,
FileData &Data) {
Data.Name = Status.getName();
Data.Size = Status.getSize();
Data.ModTime = llvm::sys::toTimeT(Status.getLastModificationTime());
Data.UniqueID = Status.getUniqueID();
Data.IsDirectory = Status.isDirectory();
Data.IsNamedPipe = Status.getType() == llvm::sys::fs::file_type::fifo_file;
Data.InPCH = false;
Data.IsVFSMapped = Status.IsVFSMapped;
}
/// FileSystemStatCache::get - Get the 'stat' information for the specified
/// path, using the cache to accelerate it if possible. This returns true if
/// the path does not exist or false if it exists.
///
/// If isFile is true, then this lookup should only return success for files
/// (not directories). If it is false this lookup should only return
/// success for directories (not files). On a successful file lookup, the
/// implementation can optionally fill in FileDescriptor with a valid
/// descriptor and the client guarantees that it will close it.
bool FileSystemStatCache::get(StringRef Path, FileData &Data, bool isFile,
std::unique_ptr<llvm::vfs::File> *F,
FileSystemStatCache *Cache,
llvm::vfs::FileSystem &FS) {
LookupResult R;
bool isForDir = !isFile;
// If we have a cache, use it to resolve the stat query.
if (Cache)
R = Cache->getStat(Path, Data, isFile, F, FS);
else if (isForDir || !F) {
// If this is a directory or a file descriptor is not needed and we have
// no cache, just go to the file system.
llvm::ErrorOr<llvm::vfs::Status> Status = FS.status(Path);
if (!Status) {
R = CacheMissing;
} else {
R = CacheExists;
copyStatusToFileData(*Status, Data);
}
} else {
// Otherwise, we have to go to the filesystem. We can always just use
// 'stat' here, but (for files) the client is asking whether the file exists
// because it wants to turn around and *open* it. It is more efficient to
// do "open+fstat" on success than it is to do "stat+open".
//
// Because of this, check to see if the file exists with 'open'. If the
// open succeeds, use fstat to get the stat info.
auto OwnedFile = FS.openFileForRead(Path);
if (!OwnedFile) {
// If the open fails, our "stat" fails.
R = CacheMissing;
} else {
// Otherwise, the open succeeded. Do an fstat to get the information
// about the file. We'll end up returning the open file descriptor to the
// client to do what they please with it.
llvm::ErrorOr<llvm::vfs::Status> Status = (*OwnedFile)->status();
if (Status) {
R = CacheExists;
copyStatusToFileData(*Status, Data);
*F = std::move(*OwnedFile);
} else {
// fstat rarely fails. If it does, claim the initial open didn't
// succeed.
R = CacheMissing;
*F = nullptr;
}
}
}
// If the path doesn't exist, return failure.
if (R == CacheMissing) return true;
// If the path exists, make sure that its "directoryness" matches the clients
// demands.
if (Data.IsDirectory != isForDir) {
// If not, close the file if opened.
if (F)
*F = nullptr;
return true;
}
return false;
}
MemorizeStatCalls::LookupResult
MemorizeStatCalls::getStat(StringRef Path, FileData &Data, bool isFile,
std::unique_ptr<llvm::vfs::File> *F,
llvm::vfs::FileSystem &FS) {
if (get(Path, Data, isFile, F, nullptr, FS)) {
// Do not cache failed stats, it is easy to construct common inconsistent
// situations if we do, and they are not important for PCH performance
// (which currently only needs the stats to construct the initial
// FileManager entries).
return CacheMissing;
}
// Cache file 'stat' results and directories with absolutely paths.
if (!Data.IsDirectory || llvm::sys::path::is_absolute(Path))
StatCalls[Path] = Data;
return CacheExists;
}
|
