source: Evidence/Config.cc@ 152

Last change on this file since 152 was 151, checked in by ogrimm, 13 years ago
DColl publishes also current data file name
File size: 5.1 KB
Line 
1/********************************************************************\
2
3 Configuration server for the Evidence Control System
4
5 - The configuration file is opened without buffering to catch changes
6 without closing/opening.
7 - The name of a configuration file can be given as command line argument
8 - If a configuration file change is detected through inotify, the service
9 "Config/ModifyTime" is updated with the current UNIX time to inform applications.
10 The initial value of the server is the last file modification time.
11 - The employed line buffer has conservatively at least the size of the
12 configuration file. If needed, it will be enlarged.
13
14 Oliver Grimm, November 2009
15
16\********************************************************************/
17
18#define DEFAULT_CONFIG "../config/Evidence.conf"
19#define SERVER_NAME "Config"
20
21#include "Evidence.h"
22
23#include <ctype.h>
24#include <sys/stat.h>
25#include <sys/inotify.h>
26
27//
28// Class derived from DimRpc
29//
30class EvidenceConfig: public DimRpc, public EvidenceServer {
31
32 private:
33 FILE *File;
34 char *Buffer;
35 unsigned int BufferLength;
36 DimService *ConfigModified;
37 int ModifyTime;
38
39 void rpcHandler();
40
41 public:
42 EvidenceConfig(const char *);
43 ~EvidenceConfig();
44
45 void ConfigChanged();
46};
47
48// Constructor
49EvidenceConfig::EvidenceConfig(const char *Filename):
50 DimRpc("ConfigRequest", "C", "C"), EvidenceServer(SERVER_NAME) {
51
52 // Open configuration file
53 if ((File = fopen(Filename, "r")) == NULL) {
54 State(FATAL, "Could not open configuration file '%s' (%s)\n", Filename, strerror(errno));
55 }
56
57 // Create DIM service to indicate changes of configuration file
58 struct stat Stat;
59 if (stat(Filename, &Stat) == -1) {
60 State(WARN, "Could not read last modification time of configuration file '%s' (%s)", Filename, strerror(errno));
61 ModifyTime = 0;
62 }
63 else ModifyTime = Stat.st_mtime;
64 ConfigModified = new DimService (SERVER_NAME"/ModifyTime", ModifyTime);
65
66 // Disable buffering, so file modifications are immediately seen
67 if (setvbuf(File, NULL, _IONBF, 0) != 0) {
68 State(WARN, "Error setting configuration file '%s' to unbuffered mode", Filename);
69 }
70
71 Buffer = NULL; // Will be allocated in rpcHandler()
72 BufferLength = 0;
73}
74
75// Destructor
76EvidenceConfig::~EvidenceConfig() {
77
78 if (File != NULL) fclose(File);
79 delete[] Buffer;
80}
81
82// Implementation of response to configuration request
83void EvidenceConfig::rpcHandler() {
84
85 char *Token1,*Token2,*Token3, *Request = getString();
86 struct stat FileStatus;
87
88 // Check if Buffer[] is large enough to hold full file, enlarge if necessary
89 if (fstat(fileno(File), &FileStatus) == -1) {
90 State(FATAL, "Could not determine size of configuration file to allocate buffer (%s)", strerror(errno));
91 }
92 else if(BufferLength < FileStatus.st_size) {
93 delete[] Buffer;
94 Buffer = new char [FileStatus.st_size];
95 BufferLength = FileStatus.st_size;
96 }
97
98 // Search for configuration item
99 rewind(File);
100 while (fgets(Buffer, BufferLength, File) != NULL) {
101
102 // Combine lines that end with '+'
103 while (Buffer[strlen(Buffer)-2] == '+') {
104 if (fgets(Buffer+strlen(Buffer)-2, BufferLength-(strlen(Buffer)-2), File) == NULL) break;
105 }
106
107 // Ignore comments
108 for (int i=0; i<strlen(Buffer); i++) if (Buffer[i] == '#') Buffer[i] = '\0';
109
110 // Extract tokens
111 Token1 = strtok(Buffer, " \t:");
112 Token2 = strtok(NULL, " \t:");
113 Token3 = strtok(NULL, "\n");
114
115 // Check if all tokens existing
116 if(Token1==NULL || Token2==NULL || Token3==NULL) continue;
117
118 // Check for match and then send data (removing trainlin whitespace)
119 if (strstr(Request, Token1)!=NULL && strstr(Request, Token2)!=NULL) {
120 while (isspace(*Token3) != 0) Token3++;
121 setData(Token3);
122 break;
123 }
124 }
125
126 // If configuration data not found, send empty string
127 if (feof(File)!=0) setData((char *) "");
128
129 State(INFO, "Client '%s' (ID %d) requested '%s'. Send '%s'.",
130 DimServer::getClientName(),
131 DimServer::getClientId(),
132 Request, feof(File)!=0 ? "n/a" : Token3);
133}
134
135// Signalisation of configuration change
136void EvidenceConfig::ConfigChanged() {
137
138 ModifyTime = time(NULL);
139 ConfigModified->updateService();
140}
141
142//
143// Declaring class static ensures destructor is called when exit() is invoked
144//
145int main(int argc, char *argv[]) {
146
147 static EvidenceConfig Config(argc<2 ? DEFAULT_CONFIG : argv[1]);
148
149 int Notify;
150 struct inotify_event Event;
151
152 if ((Notify = inotify_init()) == -1) {
153 Config.State(EvidenceConfig::WARN, "inotify_init() failed, cannot monitor changes of configuration file (%s)\n", strerror(errno));
154 }
155 else if (inotify_add_watch(Notify, argc<2 ? DEFAULT_CONFIG : argv[1], IN_MODIFY) == -1) {
156 Config.State(EvidenceConfig::WARN, "Could not set inotify watch on configuration file (%s)\n", strerror(errno));
157 close(Notify);
158 Notify = -1;
159 }
160
161 // Sleep until file changes or signal caught
162 while (!EvidenceServer::ExitRequest) {
163 if (Notify != -1) {
164 read(Notify, &Event, sizeof(Event));
165 Config.ConfigChanged();
166 }
167 else pause();
168 }
169
170 if (Notify != -1) close(Notify);
171}
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