LLVM  9.0.0svn
Process.h
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1 //===- llvm/Support/Process.h -----------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 /// \file
9 ///
10 /// Provides a library for accessing information about this process and other
11 /// processes on the operating system. Also provides means of spawning
12 /// subprocess for commands. The design of this library is modeled after the
13 /// proposed design of the Boost.Process library, and is design specifically to
14 /// follow the style of standard libraries and potentially become a proposal
15 /// for a standard library.
16 ///
17 /// This file declares the llvm::sys::Process class which contains a collection
18 /// of legacy static interfaces for extracting various information about the
19 /// current process. The goal is to migrate users of this API over to the new
20 /// interfaces.
21 ///
22 //===----------------------------------------------------------------------===//
23 
24 #ifndef LLVM_SUPPORT_PROCESS_H
25 #define LLVM_SUPPORT_PROCESS_H
26 
27 #include "llvm/ADT/Optional.h"
28 #include "llvm/Support/Allocator.h"
29 #include "llvm/Support/Chrono.h"
30 #include "llvm/Support/DataTypes.h"
31 #include <system_error>
32 
33 namespace llvm {
34 template <typename T> class ArrayRef;
35 class StringRef;
36 
37 namespace sys {
38 
39 
40 /// A collection of legacy interfaces for querying information about the
41 /// current executing process.
42 class Process {
43 public:
44  static unsigned getPageSize();
45 
46  /// Return process memory usage.
47  /// This static function will return the total amount of memory allocated
48  /// by the process. This only counts the memory allocated via the malloc,
49  /// calloc and realloc functions and includes any "free" holes in the
50  /// allocated space.
51  static size_t GetMallocUsage();
52 
53  /// This static function will set \p user_time to the amount of CPU time
54  /// spent in user (non-kernel) mode and \p sys_time to the amount of CPU
55  /// time spent in system (kernel) mode. If the operating system does not
56  /// support collection of these metrics, a zero duration will be for both
57  /// values.
58  /// \param elapsed Returns the system_clock::now() giving current time
59  /// \param user_time Returns the current amount of user time for the process
60  /// \param sys_time Returns the current amount of system time for the process
61  static void GetTimeUsage(TimePoint<> &elapsed,
62  std::chrono::nanoseconds &user_time,
63  std::chrono::nanoseconds &sys_time);
64 
65  /// This function makes the necessary calls to the operating system to
66  /// prevent core files or any other kind of large memory dumps that can
67  /// occur when a program fails.
68  /// Prevent core file generation.
69  static void PreventCoreFiles();
70 
71  /// true if PreventCoreFiles has been called, false otherwise.
72  static bool AreCoreFilesPrevented();
73 
74  // This function returns the environment variable \arg name's value as a UTF-8
75  // string. \arg Name is assumed to be in UTF-8 encoding too.
77 
78  /// This function searches for an existing file in the list of directories
79  /// in a PATH like environment variable, and returns the first file found,
80  /// according to the order of the entries in the PATH like environment
81  /// variable. If an ignore list is specified, then any folder which is in
82  /// the PATH like environment variable but is also in IgnoreList is not
83  /// considered.
85  StringRef FileName,
86  ArrayRef<std::string> IgnoreList);
87 
89  StringRef FileName);
90 
91  // This functions ensures that the standard file descriptors (input, output,
92  // and error) are properly mapped to a file descriptor before we use any of
93  // them. This should only be called by standalone programs, library
94  // components should not call this.
95  static std::error_code FixupStandardFileDescriptors();
96 
97  // This function safely closes a file descriptor. It is not safe to retry
98  // close(2) when it returns with errno equivalent to EINTR; this is because
99  // *nixen cannot agree if the file descriptor is, in fact, closed when this
100  // occurs.
101  //
102  // N.B. Some operating systems, due to thread cancellation, cannot properly
103  // guarantee that it will or will not be closed one way or the other!
104  static std::error_code SafelyCloseFileDescriptor(int FD);
105 
106  /// This function determines if the standard input is connected directly
107  /// to a user's input (keyboard probably), rather than coming from a file
108  /// or pipe.
109  static bool StandardInIsUserInput();
110 
111  /// This function determines if the standard output is connected to a
112  /// "tty" or "console" window. That is, the output would be displayed to
113  /// the user rather than being put on a pipe or stored in a file.
114  static bool StandardOutIsDisplayed();
115 
116  /// This function determines if the standard error is connected to a
117  /// "tty" or "console" window. That is, the output would be displayed to
118  /// the user rather than being put on a pipe or stored in a file.
119  static bool StandardErrIsDisplayed();
120 
121  /// This function determines if the given file descriptor is connected to
122  /// a "tty" or "console" window. That is, the output would be displayed to
123  /// the user rather than being put on a pipe or stored in a file.
124  static bool FileDescriptorIsDisplayed(int fd);
125 
126  /// This function determines if the given file descriptor is displayd and
127  /// supports colors.
128  static bool FileDescriptorHasColors(int fd);
129 
130  /// This function determines the number of columns in the window
131  /// if standard output is connected to a "tty" or "console"
132  /// window. If standard output is not connected to a tty or
133  /// console, or if the number of columns cannot be determined,
134  /// this routine returns zero.
135  static unsigned StandardOutColumns();
136 
137  /// This function determines the number of columns in the window
138  /// if standard error is connected to a "tty" or "console"
139  /// window. If standard error is not connected to a tty or
140  /// console, or if the number of columns cannot be determined,
141  /// this routine returns zero.
142  static unsigned StandardErrColumns();
143 
144  /// This function determines whether the terminal connected to standard
145  /// output supports colors. If standard output is not connected to a
146  /// terminal, this function returns false.
147  static bool StandardOutHasColors();
148 
149  /// This function determines whether the terminal connected to standard
150  /// error supports colors. If standard error is not connected to a
151  /// terminal, this function returns false.
152  static bool StandardErrHasColors();
153 
154  /// Enables or disables whether ANSI escape sequences are used to output
155  /// colors. This only has an effect on Windows.
156  /// Note: Setting this option is not thread-safe and should only be done
157  /// during initialization.
158  static void UseANSIEscapeCodes(bool enable);
159 
160  /// Whether changing colors requires the output to be flushed.
161  /// This is needed on systems that don't support escape sequences for
162  /// changing colors.
163  static bool ColorNeedsFlush();
164 
165  /// This function returns the colorcode escape sequences.
166  /// If ColorNeedsFlush() is true then this function will change the colors
167  /// and return an empty escape sequence. In that case it is the
168  /// responsibility of the client to flush the output stream prior to
169  /// calling this function.
170  static const char *OutputColor(char c, bool bold, bool bg);
171 
172  /// Same as OutputColor, but only enables the bold attribute.
173  static const char *OutputBold(bool bg);
174 
175  /// This function returns the escape sequence to reverse forground and
176  /// background colors.
177  static const char *OutputReverse();
178 
179  /// Resets the terminals colors, or returns an escape sequence to do so.
180  static const char *ResetColor();
181 
182  /// Get the result of a process wide random number generator. The
183  /// generator will be automatically seeded in non-deterministic fashion.
184  static unsigned GetRandomNumber();
185 };
186 
187 }
188 }
189 
190 #endif
This class represents lattice values for constants.
Definition: AllocatorList.h:23
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:89
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:32
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:35
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:42
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:48
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:33