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Process.h
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1 //===- llvm/Support/Process.h -----------------------------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 /// \file
10 ///
11 /// Provides a library for accessing information about this process and other
12 /// processes on the operating system. Also provides means of spawning
13 /// subprocess for commands. The design of this library is modeled after the
14 /// proposed design of the Boost.Process library, and is design specifically to
15 /// follow the style of standard libraries and potentially become a proposal
16 /// for a standard library.
17 ///
18 /// This file declares the llvm::sys::Process class which contains a collection
19 /// of legacy static interfaces for extracting various information about the
20 /// current process. The goal is to migrate users of this API over to the new
21 /// interfaces.
22 ///
23 //===----------------------------------------------------------------------===//
24 
25 #ifndef LLVM_SUPPORT_PROCESS_H
26 #define LLVM_SUPPORT_PROCESS_H
27 
28 #include "llvm/ADT/Optional.h"
29 #include "llvm/Support/Allocator.h"
30 #include "llvm/Support/Chrono.h"
31 #include "llvm/Support/DataTypes.h"
32 #include <system_error>
33 
34 namespace llvm {
35 template <typename T> class ArrayRef;
36 class StringRef;
37 
38 namespace sys {
39 
40 
41 /// A collection of legacy interfaces for querying information about the
42 /// current executing process.
43 class Process {
44 public:
45  static unsigned getPageSize();
46 
47  /// Return process memory usage.
48  /// This static function will return the total amount of memory allocated
49  /// by the process. This only counts the memory allocated via the malloc,
50  /// calloc and realloc functions and includes any "free" holes in the
51  /// allocated space.
52  static size_t GetMallocUsage();
53 
54  /// This static function will set \p user_time to the amount of CPU time
55  /// spent in user (non-kernel) mode and \p sys_time to the amount of CPU
56  /// time spent in system (kernel) mode. If the operating system does not
57  /// support collection of these metrics, a zero duration will be for both
58  /// values.
59  /// \param elapsed Returns the system_clock::now() giving current time
60  /// \param user_time Returns the current amount of user time for the process
61  /// \param sys_time Returns the current amount of system time for the process
62  static void GetTimeUsage(TimePoint<> &elapsed,
63  std::chrono::nanoseconds &user_time,
64  std::chrono::nanoseconds &sys_time);
65 
66  /// This function makes the necessary calls to the operating system to
67  /// prevent core files or any other kind of large memory dumps that can
68  /// occur when a program fails.
69  /// Prevent core file generation.
70  static void PreventCoreFiles();
71 
72  /// true if PreventCoreFiles has been called, false otherwise.
73  static bool AreCoreFilesPrevented();
74 
75  // This function returns the environment variable \arg name's value as a UTF-8
76  // string. \arg Name is assumed to be in UTF-8 encoding too.
78 
79  /// This function searches for an existing file in the list of directories
80  /// in a PATH like environment variable, and returns the first file found,
81  /// according to the order of the entries in the PATH like environment
82  /// variable. If an ignore list is specified, then any folder which is in
83  /// the PATH like environment variable but is also in IgnoreList is not
84  /// considered.
86  StringRef FileName,
87  ArrayRef<std::string> IgnoreList);
88 
90  StringRef FileName);
91 
92  // This functions ensures that the standard file descriptors (input, output,
93  // and error) are properly mapped to a file descriptor before we use any of
94  // them. This should only be called by standalone programs, library
95  // components should not call this.
96  static std::error_code FixupStandardFileDescriptors();
97 
98  // This function safely closes a file descriptor. It is not safe to retry
99  // close(2) when it returns with errno equivalent to EINTR; this is because
100  // *nixen cannot agree if the file descriptor is, in fact, closed when this
101  // occurs.
102  //
103  // N.B. Some operating systems, due to thread cancellation, cannot properly
104  // guarantee that it will or will not be closed one way or the other!
105  static std::error_code SafelyCloseFileDescriptor(int FD);
106 
107  /// This function determines if the standard input is connected directly
108  /// to a user's input (keyboard probably), rather than coming from a file
109  /// or pipe.
110  static bool StandardInIsUserInput();
111 
112  /// This function determines if the standard output is connected to a
113  /// "tty" or "console" window. That is, the output would be displayed to
114  /// the user rather than being put on a pipe or stored in a file.
115  static bool StandardOutIsDisplayed();
116 
117  /// This function determines if the standard error is connected to a
118  /// "tty" or "console" window. That is, the output would be displayed to
119  /// the user rather than being put on a pipe or stored in a file.
120  static bool StandardErrIsDisplayed();
121 
122  /// This function determines if the given file descriptor is connected to
123  /// a "tty" or "console" window. That is, the output would be displayed to
124  /// the user rather than being put on a pipe or stored in a file.
125  static bool FileDescriptorIsDisplayed(int fd);
126 
127  /// This function determines if the given file descriptor is displayd and
128  /// supports colors.
129  static bool FileDescriptorHasColors(int fd);
130 
131  /// This function determines the number of columns in the window
132  /// if standard output is connected to a "tty" or "console"
133  /// window. If standard output is not connected to a tty or
134  /// console, or if the number of columns cannot be determined,
135  /// this routine returns zero.
136  static unsigned StandardOutColumns();
137 
138  /// This function determines the number of columns in the window
139  /// if standard error is connected to a "tty" or "console"
140  /// window. If standard error is not connected to a tty or
141  /// console, or if the number of columns cannot be determined,
142  /// this routine returns zero.
143  static unsigned StandardErrColumns();
144 
145  /// This function determines whether the terminal connected to standard
146  /// output supports colors. If standard output is not connected to a
147  /// terminal, this function returns false.
148  static bool StandardOutHasColors();
149 
150  /// This function determines whether the terminal connected to standard
151  /// error supports colors. If standard error is not connected to a
152  /// terminal, this function returns false.
153  static bool StandardErrHasColors();
154 
155  /// Enables or disables whether ANSI escape sequences are used to output
156  /// colors. This only has an effect on Windows.
157  /// Note: Setting this option is not thread-safe and should only be done
158  /// during initialization.
159  static void UseANSIEscapeCodes(bool enable);
160 
161  /// Whether changing colors requires the output to be flushed.
162  /// This is needed on systems that don't support escape sequences for
163  /// changing colors.
164  static bool ColorNeedsFlush();
165 
166  /// This function returns the colorcode escape sequences.
167  /// If ColorNeedsFlush() is true then this function will change the colors
168  /// and return an empty escape sequence. In that case it is the
169  /// responsibility of the client to flush the output stream prior to
170  /// calling this function.
171  static const char *OutputColor(char c, bool bold, bool bg);
172 
173  /// Same as OutputColor, but only enables the bold attribute.
174  static const char *OutputBold(bool bg);
175 
176  /// This function returns the escape sequence to reverse forground and
177  /// background colors.
178  static const char *OutputReverse();
179 
180  /// Resets the terminals colors, or returns an escape sequence to do so.
181  static const char *ResetColor();
182 
183  /// Get the result of a process wide random number generator. The
184  /// generator will be automatically seeded in non-deterministic fashion.
185  static unsigned GetRandomNumber();
186 };
187 
188 }
189 }
190 
191 #endif
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
static const char * ResetColor()
Resets the terminals colors, or returns an escape sequence to do so.
static const char * OutputColor(char c, bool bold, bool bg)
This function returns the colorcode escape sequences.
static bool StandardErrHasColors()
This function determines whether the terminal connected to standard error supports colors...
static bool FileDescriptorHasColors(int fd)
This function determines if the given file descriptor is displayd and supports colors.
static bool AreCoreFilesPrevented()
true if PreventCoreFiles has been called, false otherwise.
Definition: Process.cpp:90
static bool FileDescriptorIsDisplayed(int fd)
This function determines if the given file descriptor is connected to a "tty" or "console" window...
This file defines the MallocAllocator and BumpPtrAllocator interfaces.
static std::error_code FixupStandardFileDescriptors()
static bool ColorNeedsFlush()
Whether changing colors requires the output to be flushed.
static const char * OutputReverse()
This function returns the escape sequence to reverse forground and background colors.
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:33
static bool StandardInIsUserInput()
This function determines if the standard input is connected directly to a user&#39;s input (keyboard prob...
static bool StandardOutIsDisplayed()
This function determines if the standard output is connected to a "tty" or "console" window...
static void UseANSIEscapeCodes(bool enable)
Enables or disables whether ANSI escape sequences are used to output colors.
static unsigned StandardOutColumns()
This function determines the number of columns in the window if standard output is connected to a "tt...
static Optional< std::string > FindInEnvPath(StringRef EnvName, StringRef FileName, ArrayRef< std::string > IgnoreList)
This function searches for an existing file in the list of directories in a PATH like environment var...
Definition: Process.cpp:36
static size_t GetMallocUsage()
Return process memory usage.
static unsigned getPageSize()
static bool StandardErrIsDisplayed()
This function determines if the standard error is connected to a "tty" or "console" window...
static void PreventCoreFiles()
This function makes the necessary calls to the operating system to prevent core files or any other ki...
static unsigned StandardErrColumns()
This function determines the number of columns in the window if standard error is connected to a "tty...
static bool StandardOutHasColors()
This function determines whether the terminal connected to standard output supports colors...
A collection of legacy interfaces for querying information about the current executing process...
Definition: Process.h:43
static unsigned GetRandomNumber()
Get the result of a process wide random number generator.
static void GetTimeUsage(TimePoint<> &elapsed, std::chrono::nanoseconds &user_time, std::chrono::nanoseconds &sys_time)
This static function will set user_time to the amount of CPU time spent in user (non-kernel) mode and...
static const char * OutputBold(bool bg)
Same as OutputColor, but only enables the bold attribute.
static const char * name
static std::error_code SafelyCloseFileDescriptor(int FD)
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
static Optional< std::string > GetEnv(StringRef name)
std::chrono::time_point< std::chrono::system_clock, D > TimePoint
A time point on the system clock.
Definition: Chrono.h:34