Class: FileSystemWatcher

Inherits:
Object show all
Includes:
ServiceState
Defined in:
lib/doozer/watcher.rb

Overview

This class will watch a directory or a set of directories and alert you of new files, modified files, deleted files. You can optionally only be alerted when a files md5 hash has been changed so you only are alerted to real changes. this of course means slower performance and higher cpu/io usage.

Constant Summary collapse

CREATED = 
0
MODIFIED = 
1
DELETED = 
2

Constants included from ServiceState

ServiceState::CONFIGURED, ServiceState::NOT_STARTED, ServiceState::STARTED, ServiceState::STOPPED

Instance Attribute Summary collapse

Attributes included from ServiceState

#endTime, #startTime

Instance Method Summary collapse

Methods included from ServiceState

#initializeState, #isConfigured?, #isStarted?, #isStopped?, #onStateChange, #setState, #stopWhen

Constructor Details

#initialize(dir = nil, expression = "**/*") ⇒ FileSystemWatcher

Returns a new instance of FileSystemWatcher.



98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
 
# File 'lib/doozer/watcher.rb', line 98

def initialize(dir=nil, expression="**/*")
  @sleepTime = 5
  @useMD5 = false
  @priority = 0
  @stopWhen = nil

  @directories = Array.new()
  @files = Array.new()

  @foundFiles = nil
  @firstLoad = true
  @watchThread = nil
  
  initializeState()

  if dir then
    addDirectory(dir, expression)
  end
end

Instance Attribute Details

#directories ⇒ Object

Returns the value of attribute directories.



96
97
98
 
# File 'lib/doozer/watcher.rb', line 96

def directories
  @directories
end

#files ⇒ Object

Returns the value of attribute files.



96
97
98
 
# File 'lib/doozer/watcher.rb', line 96

def files
  @files
end

#foundFiles ⇒ Object

Returns the value of attribute foundFiles.



96
97
98
 
# File 'lib/doozer/watcher.rb', line 96

def foundFiles
  @foundFiles
end

#mongrel ⇒ Object

the time to wait before checking the directories again



91
92
93
 
# File 'lib/doozer/watcher.rb', line 91

def mongrel
  @mongrel
end

#priority ⇒ Object

the time to wait before checking the directories again



91
92
93
 
# File 'lib/doozer/watcher.rb', line 91

def priority
  @priority
end

#sleepTime ⇒ Object

the time to wait before checking the directories again



91
92
93
 
# File 'lib/doozer/watcher.rb', line 91

def sleepTime
  @sleepTime
end

#useMD5 ⇒ Object

you can optionally use the file contents md5 to detect if a file has changed



94
95
96
 
# File 'lib/doozer/watcher.rb', line 94

def useMD5
  @useMD5
end

Instance Method Details

#addDirectory(dir, expression = "**/*") ⇒ Object

add a directory to be watched

Parameters:

  • dir —

    the directory to watch

  • expression (defaults to: "**/*") —

    the glob pattern to search under the watched directory



121
122
123
124
125
126
127
 
# File 'lib/doozer/watcher.rb', line 121

def addDirectory(dir, expression="**/*")
  if FileTest.exists?(dir) && FileTest.readable?(dir) then
    @directories << FSWatcher::Directory.new(dir, expression)
  else
    raise FSWatcher::InvalidDirectoryError, "Dir '#{dir}' either doesnt exist or isnt readable"
  end
end

#addFile(file) ⇒ Object

add a specific file to the watch list

Parameters:

  • file —

    the file to watch



135
136
137
138
139
140
141
 
# File 'lib/doozer/watcher.rb', line 135

def addFile(file)
  if FileTest.exists?(file) && FileTest.readable?(file) then
    @files << file
  else
    raise FSWatcher::InvalidFileError, "File '#{file}' either doesnt exist or isnt readable"
  end
end

#join ⇒ Object

wait for the filewatcher to finish



215
216
217
 
# File 'lib/doozer/watcher.rb', line 215

def join()
  @watchThread.join() if @watchThread
end

#removeDirectory(dir) ⇒ Object 



129
130
131
 
# File 'lib/doozer/watcher.rb', line 129

def removeDirectory(dir)
  @directories.delete(dir)
end

#removeFile(file) ⇒ Object 



143
144
145
 
# File 'lib/doozer/watcher.rb', line 143

def removeFile(file)
  @files.delete(file)
end

#start(&block) ⇒ Object

start watching the specified files/directories



148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
 
# File 'lib/doozer/watcher.rb', line 148

def start(&block)
  if isStarted? then
    raise RuntimeError, "already started"
  end

  setState(STARTED)

  @firstLoad = true
  @foundFiles = Hash.new()

  # we watch in a new thread
  @watchThread = Thread.new {
    # we will be stopped if someone calls stop or if someone set a stopWhen that becomes true
    while !isStopped? do
     if (!@directories.empty?) or (!@files.empty?) then	
    	  # this will hold the list of the files we looked at this iteration
    	  # allows us to not look at the same file again and also to compare
    	  # with the foundFile list to see if something was deleted
    	  alreadyExamined = Hash.new()
 
    	  # check the files in each watched directory
    	  if not @directories.empty? then
    	    @directories.each { | dirObj |
    	      examineFileList(dirObj.getFiles(), alreadyExamined, &block)
    	    }
    	  end
 
    	  # now examine any files the user wants to specifically watch
    	  examineFileList(@files, alreadyExamined, &block) if not @files.empty?
 
    	  # see if we have to delete files from our found list
    	  if not @firstLoad then
    	    if not @foundFiles.empty? then
    	      # now diff the found files and the examined files to see if
    	      # something has been deleted
    	      allFoundFiles = @foundFiles.keys()
    	      allExaminedFiles = alreadyExamined.keys()
    	      intersection = allFoundFiles - allExaminedFiles
    	      intersection.each { |fileName|
                # callback
                block.call(DELETED, fileName)
                # remove deleted file from the foundFiles list
                @foundFiles.delete(fileName)
              }	  
            end
          else
            @firstLoad = false
          end
        end

        # go to sleep
        sleep(@sleepTime)
      end
    }
  
  # set the watch thread priority
  @watchThread.priority = @priority

end

#stop ⇒ Object

kill the filewatcher thread



209
210
211
212
 
# File 'lib/doozer/watcher.rb', line 209

def stop()
  setState(STOPPED)
  @watchThread.wakeup()
end