Class: PcaprLocal::Xtractr::Instance

Inherits:
Object
  • Object
show all
Defined in:
lib/pcapr_local/xtractr/instance.rb

Defined Under Namespace

Classes: XtractrStartupException

Constant Summary collapse

MAX_START_TIME =

Start xtractr

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RE_STARTED = 
/starting on http:/i

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(index_dir, xtractr_path) ⇒ Instance

Returns a new instance of Instance.



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# File 'lib/pcapr_local/xtractr/instance.rb', line 14

def initialize index_dir, xtractr_path
    @index_dir = index_dir
    @xtractr_path = xtractr_path
    @lock = Mutex.new
    @last_use = Time.new.to_f # for idle timeouts
    @pid = nil
    @port = nil
end

Instance Attribute Details

#last_use ⇒ Object (readonly)

Returns the value of attribute last_use.



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# File 'lib/pcapr_local/xtractr/instance.rb', line 12

def last_use
  @last_use
end

#lock ⇒ Object (readonly)

Returns the value of attribute lock.



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# File 'lib/pcapr_local/xtractr/instance.rb', line 12

def lock
  @lock
end

#pid ⇒ Object (readonly)

Returns the value of attribute pid.



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# File 'lib/pcapr_local/xtractr/instance.rb', line 12

def pid
  @pid
end

#port ⇒ Object (readonly)

Returns the value of attribute port.



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# File 'lib/pcapr_local/xtractr/instance.rb', line 12

def port
  @port
end

Class Method Details

.free_local_port ⇒ Object

Pick a random port over 10000 and verify that it can be bound to (on localhost)



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# File 'lib/pcapr_local/xtractr/instance.rb', line 151

def self.free_local_port
    while true
        port = rand(0xffff-10000) + 10000
        socket = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)
        socket.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1)
        addr = Socket.pack_sockaddr_in(port, '127.0.0.1')
        begin
            socket.bind addr
            return port
        rescue Errno::EADDRINUSE
            next # port in use
        ensure
            socket.close
        end
    end
end

Instance Method Details

#do_start ⇒ Object 



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# File 'lib/pcapr_local/xtractr/instance.rb', line 81

def do_start 
    port = Instance.free_local_port
    command = [@xtractr_path, 'browse', @index_dir, '--port', port.to_s]
    Logger.debug "running: #{command.inspect}"
    xtractr_out = Tempfile.new "xtractr_out"
    pid = fork do
        # Xtractr forks a child process. Set process group so we
        # can send signal to all processes in a group.
        Process.setpgid $$, $$
        STDOUT.reopen xtractr_out
        STDERR.reopen xtractr_out
        Dir.chdir @index_dir
        exec *command 
    end

    begin
        Timeout.timeout MAX_START_TIME do 
            # Wait for "starting" line.
            while xtractr_out.grep(/starting on http:\/\/127\.0\.0\.1:#{port}/i).empty?
                xtractr_out.rewind
                sleep 0.01
            end
            # Sanity check that server is up.
            Net::HTTP.start('127.0.0.1', port) do |http|
                http.options("/")
            end
        end
    rescue Timeout::Error, SystemCallError
        Logger.error "Xtractr failed to start on port #{port}"
        xtractr_out.rewind
        Logger.error "Xtractr output: #{xtractr_out.read.inspect}"
        kind_kill -pid
        raise XtractrStartupException, "Timeout waiting for xtractr to startup"
    end
    
    @last_use = Time.new.to_f
    @pid = pid
    @port = port
end

#get(path_and_params) ⇒ Object

Does GET request and returns response headers and body.



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# File 'lib/pcapr_local/xtractr/instance.rb', line 24

def get path_and_params
    start if not @pid
    @lock.synchronize do
        @last_use = Time.new.to_f

        # Make request to xtractr
        uri = URI.parse("http://127.0.0.1:#{@port}/#{path_and_params}")
        response = Net::HTTP.get_response(uri)

        # Copy headers from response
        headers = {}
        response.each_header {|name,val| headers[name] = val}

        return response.code.to_i, headers, response.body
    end
end

#kind_kill(pid, wait = 1) ⇒ Object

Sends SIGTERM and waits for process to exit. If process does not exit within wait period, sends SIGKILL. Use a negative pid to kill all members of a process group.



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# File 'lib/pcapr_local/xtractr/instance.rb', line 132

def kind_kill pid, wait=1
    begin
        Process.kill 15, pid
        # Wait for process (or all group members) to
        # exit.
        Timeout.timeout wait do
            loop { Process.wait(pid) }
        end
    rescue Errno::ECHILD, Errno::ESRCH
        # Processes is dead or group has no members.
        return 
    rescue Timeout::Error, StandardError
        # Process did not shutdown in time (or there
        # was an unexpected error).
        Process.kill(9, pid) rescue nil
    end
end

#post(path_and_params, post_body) ⇒ Object

Does POST request and returns response headers and body.



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# File 'lib/pcapr_local/xtractr/instance.rb', line 42

def post path_and_params, post_body
    start if not @pid
    @lock.synchronize do
        @last_use = Time.new.to_f

        # Make request to xtractr
        Net::HTTP.start('localhost', @port) do |http|
            http.request_post "/#{path_and_params}", post_body do |response|
                headers = {}
                response.each_header {|name,val| headers[name] = val}
                return response.code.to_i, headers, response.body
            end
        end
    end
end

#start ⇒ Object

Starts underlying process.



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# File 'lib/pcapr_local/xtractr/instance.rb', line 59

def start
    @lock.synchronize do 
        return if @pid
        err = nil
        # There is a remote possibility that the random port we pick will be
        # in use at the moment we try to bind to it. Thus the retries.
        3.times do  |n|
            begin
                do_start
                return
            rescue => err
            end
        end
        raise err
    end
end

#stop ⇒ Object

Kills underlying xtractr process.



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# File 'lib/pcapr_local/xtractr/instance.rb', line 122

def stop
    if @pid
        kind_kill -@pid
        @pid = nil
    end
end