Here.cc
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1 /*
2  * Copyright (C) 1996-2018 The Squid Software Foundation and contributors
3  *
4  * Squid software is distributed under GPLv2+ license and includes
5  * contributions from numerous individuals and organizations.
6  * Please see the COPYING and CONTRIBUTORS files for details.
7  */
8 
9 #include "squid.h"
10 #include "base/Here.h"
11 
12 #include <iostream>
13 
14 /* File name hashing helpers */
15 
16 // Build prefix is the file system path leading to Squid src/ source directory.
17 // It is "." for in-tree builds but may be lengthy and sensitive otherwise.
18 
20 static size_t
22 {
23  // The hard-coded tail must be kept in sync with this file actual name!
24  const char *tail = "src/base/Here.cc";
25  const char *full = __FILE__;
26 
27  // Disable heuristic if it does not work.
28  if (strstr(full, tail) == 0)
29  return 0;
30 
31  return strlen(full) - strlen(tail);
32 }
33 
35 static const char *
36 SkipBuildPrefix(const char* path)
37 {
38  static const size_t ToSkip = BuildPrefixLength();
39  return path + ToSkip;
40 }
41 
43 static SourceLocationId
44 FileNameHash(const char *path)
45 {
46  // Keep in sync with FileNameHash() in scripts/calc-must-ids.pl!
47 
48  const char *name = strrchr(path, '/');
49  if (name)
50  ++name; // skip '/'
51  else
52  name = path;
53 
54  uint32_t hash = 0;
55  uint32_t iterations = 0;
56  while (*name) {
57  ++iterations;
58  hash ^= 271 * static_cast<uint32_t>(*name);
59  ++name;
60  }
61  return hash ^ (iterations * 271);
62 }
63 
64 /* SourceLocation */
65 
68 {
69  const auto fnameHashFull = fileNameHashCacher(fileName, &FileNameHash);
70  // 32 bits = 18 bits for the filename hash + 14 bits for the line number.
71  // Keep in sync with ComputeMustIds() in scripts/calc-must-ids.pl.
72  const auto fnameHash = fnameHashFull % 0x3FFFF;
73  return (fnameHash << 14) | (lineNo & 0x3FFF);
74 }
75 
76 std::ostream &
77 SourceLocation::print(std::ostream &os) const
78 {
79  if (fileName) {
81 
82  // TODO: Use more common and search-friendlier fileName:lineNo: format.
83  if (lineNo > 0)
84  os << '(' << lineNo << ')';
85  }
86  if (context) {
87  if (fileName)
88  os << ' ';
89  os << context;
90  }
91  return os;
92 }
93 
const char * context
line-independent location description
Definition: Here.h:45
SourceLocationId id() const
Definition: Here.cc:67
std::ostream & print(std::ostream &os) const
describes location using a compact but human-friendly format
Definition: Here.cc:77
int lineNo
line number inside the source file name (if positive)
Definition: Here.h:47
static SourceLocationId FileNameHash(const char *path)
quickly computes a (weak) hash of a file name
Definition: Here.cc:44
uint32_t SourceLocationId
semi-uniquely identifies a source code location; stable across Squid runs
Definition: Here.h:18
static hash_table * hash
Definition: text_backend.cc:41
const char * fileName
source file name, often relative to build path
Definition: Here.h:46
static const char * SkipBuildPrefix(const char *path)
Definition: Here.cc:36
FileNameHashCacher * fileNameHashCacher
Definition: Here.h:51
static size_t BuildPrefixLength()
Definition: Here.cc:21

 

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