Simplify backend hierarchy

CHANGELOG.md

@@ -7,6 +7,11 @@ appear at the top.
 
   * Add your entries below here, remember to credit yourself however you want
     to be credited!
+  * Simplified backend hierarchy. @robd
+    * Moved duplicate implementations of `make`, `rake`, `test`, `capture`, `background` on to `Abstract` backend.
+    * Backend implementations now only need to implement `execute_command`, `upload!` and `download!`
+    * Removed `Printer` from backend hierarchy for `Local` and `Netssh` backends (they now just extend `Abstract`)
+    * Removed unused `Net::SSH:LogLevelShim`
 
 ## 1.7.1
 

lib/sshkit/backends/abstract.rb

@@ -9,7 +9,7 @@ class Abstract
       attr_reader :host
 
       def run
-        # Nothing to do
+        instance_exec(@host, &@block)
       end
 
       def initialize(host, &block)
@@ -47,23 +47,32 @@ def trace(messages)
       end
 
       def make(commands=[])
-        raise MethodUnavailableError
+        execute :make, commands
       end
 
       def rake(commands=[])
-        raise MethodUnavailableError
+        execute :rake, commands
       end
 
-      def test(command, args=[])
-        raise MethodUnavailableError
+      def test(*args)
+        options = args.extract_options!.merge(raise_on_non_zero_exit: false, verbosity: Logger::DEBUG)
+        create_command_and_execute(args, options).success?
       end
 
-      def execute(command, args=[])
-        raise MethodUnavailableError
+      def capture(*args)
+        options = { verbosity: Logger::DEBUG }.merge(args.extract_options!)
+        create_command_and_execute(args, options).full_stdout
       end
 
-      def capture(command, args=[])
-        raise MethodUnavailableError
+      def background(*args)
+        warn "[Deprecated] The background method is deprecated. Blame badly behaved pseudo-daemons!"
+        options = args.extract_options!.merge(run_in_background: true)
+        create_command_and_execute(args, options).success?
+      end
+
+      def execute(*args)
+        options = args.extract_options!
+        create_command_and_execute(args, options).success?
       end
 
       def within(directory, &block)
@@ -118,10 +127,23 @@ def configure
         end
       end
 
+      # Backends which extend the Abstract backend should implement the following methods:
+      def upload!(local, remote, options = {}) raise MethodUnavailableError end
+      def download!(remote, local=nil, options = {}) raise MethodUnavailableError end
+      def execute_command(cmd) raise MethodUnavailableError end
+      private :execute_command # Can inline after Ruby 2.1
+
       private
 
-      def command(*args)
-        options = args.extract_options!
+      def output
+        SSHKit.config.output
+      end
+
+      def create_command_and_execute(args, options)
+        command(args, options).tap { |cmd| execute_command(cmd) }
+      end
+
+      def command(args, options)
         SSHKit::Command.new(*[*args, options.merge({in: @pwd.nil? ? nil : File.join(@pwd), env: @env, host: @host, user: @user, group: @group})])
       end
 

lib/sshkit/backends/local.rb

@@ -4,34 +4,13 @@ module SSHKit
 
   module Backend
 
-    class Local < Printer
+    class Local < Abstract
 
       def initialize(_ = nil, &block)
         @host = Host.new(:local) # just for logging
         @block = block
       end
 
-      def run
-        instance_exec(@host, &@block)
-      end
-
-      def test(*args)
-        options = args.extract_options!.merge(
-          raise_on_non_zero_exit: false,
-          verbosity: Logger::DEBUG
-        )
-        _execute(*[*args, options]).success?
-      end
-
-      def execute(*args)
-        _execute(*args).success?
-      end
-
-      def capture(*args)
-        options = { verbosity: Logger::DEBUG }.merge(args.extract_options!)
-        _execute(*[*args, options]).full_stdout
-      end
-
       def upload!(local, remote, options = {})
         if local.is_a?(String)
           FileUtils.cp(local, remote)
@@ -54,40 +33,38 @@ def download!(remote, local=nil, options = {})
 
       private
 
-      def _execute(*args)
-        command(*args).tap do |cmd|
-          output << cmd
+      def execute_command(cmd)
+        output << cmd
 
-          cmd.started = Time.now
+        cmd.started = Time.now
 
-          Open3.popen3(cmd.to_command) do |stdin, stdout, stderr, wait_thr|
-            stdout_thread = Thread.new do
-              while line = stdout.gets do
-                cmd.stdout = line
-                cmd.full_stdout += line
+        Open3.popen3(cmd.to_command) do |stdin, stdout, stderr, wait_thr|
+          stdout_thread = Thread.new do
+            while line = stdout.gets do
+              cmd.stdout = line
+              cmd.full_stdout += line
 
-                output << cmd
-              end
+              output << cmd
             end
+          end
 
-            stderr_thread = Thread.new do
-              while line = stderr.gets do
-                cmd.stderr = line
-                cmd.full_stderr += line
+          stderr_thread = Thread.new do
+            while line = stderr.gets do
+              cmd.stderr = line
+              cmd.full_stderr += line
 
-                output << cmd
-              end
+              output << cmd
             end
+          end
 
-            stdout_thread.join
-            stderr_thread.join
+          stdout_thread.join
+          stderr_thread.join
 
-            cmd.exit_status = wait_thr.value.to_i
-            cmd.stdout = ''
-            cmd.stderr = ''
+          cmd.exit_status = wait_thr.value.to_i
+          cmd.stdout = ''
+          cmd.stderr = ''
 
-            output << cmd
-          end
+          output << cmd
         end
       end
 

lib/sshkit/backends/netssh.rb

@@ -15,29 +15,9 @@ def default_files
 
 module SSHKit
 
-  class Logger
-
-    class Net::SSH::LogLevelShim
-      attr_reader :output
-      def initialize(output)
-        @output = output
-      end
-      def debug(args)
-        output << LogMessage.new(Logger::TRACE, args)
-      end
-      def error(args)
-        output << LogMessage.new(Logger::ERROR, args)
-      end
-      def lwarn(args)
-        output << LogMessage.new(Logger::WARN, args)
-      end
-    end
-
-  end
-
   module Backend
 
-    class Netssh < Printer
+    class Netssh < Abstract
 
       class Configuration
         attr_accessor :connection_timeout, :pty
@@ -48,33 +28,10 @@ def ssh_options
         end
       end
 
-      include SSHKit::CommandHelper
-
-      def run
-        instance_exec(host, &@block)
-      end
-
-      def test(*args)
-        options = args.extract_options!.merge(
-          raise_on_non_zero_exit: false,
-          verbosity: Logger::DEBUG
-        )
-        _execute(*[*args, options]).success?
-      end
-
-      def execute(*args)
-        _execute(*args).success?
-      end
-
-      def background(*args)
-        warn "[Deprecated] The background method is deprecated. Blame badly behaved pseudo-daemons!"
-        options = args.extract_options!.merge(run_in_background: true)
-        _execute(*[*args, options]).success?
-      end
-
       def capture(*args)
-        options = { verbosity: Logger::DEBUG }.merge(args.extract_options!)
-        _execute(*[*args, options]).full_stdout.strip
+        # The behaviour to strip the full stdout was removed from the local backend in commit 7d15a9a,
+        # but was left in for the net ssh backend.
+        super(*args).strip
       end
 
       def upload!(local, remote, options = {})
@@ -129,56 +86,54 @@ def transfer_summarizer(action)
         end
       end
 
-      def _execute(*args)
-        command(*args).tap do |cmd|
-          output << cmd
-          cmd.started = true
-          exit_status = nil
-          with_ssh do |ssh|
-            ssh.open_channel do |chan|
-              chan.request_pty if Netssh.config.pty
-              chan.exec cmd.to_command do |ch, success|
-                chan.on_data do |ch, data|
-                  cmd.stdout = data
-                  cmd.full_stdout += data
-                  output << cmd
-                end
-                chan.on_extended_data do |ch, type, data|
-                  cmd.stderr = data
-                  cmd.full_stderr += data
-                  output << cmd
-                end
-                chan.on_request("exit-status") do |ch, data|
-                  exit_status = data.read_long
-                end
-                #chan.on_request("exit-signal") do |ch, data|
-                #  # TODO: This gets called if the program is killed by a signal
-                #  # might also be a worthwhile thing to report
-                #  exit_signal = data.read_string.to_i
-                #  warn ">>> " + exit_signal.inspect
-                #  output << cmd
-                #end
-                chan.on_open_failed do |ch|
-                  # TODO: What do do here?
-                  # I think we should raise something
-                end
-                chan.on_process do |ch|
-                  # TODO: I don't know if this is useful
-                end
-                chan.on_eof do |ch|
-                  # TODO: chan sends EOF before the exit status has been
-                  # writtend
-                end
+      def execute_command(cmd)
+        output << cmd
+        cmd.started = true
+        exit_status = nil
+        with_ssh do |ssh|
+          ssh.open_channel do |chan|
+            chan.request_pty if Netssh.config.pty
+            chan.exec cmd.to_command do |ch, success|
+              chan.on_data do |ch, data|
+                cmd.stdout = data
+                cmd.full_stdout += data
+                output << cmd
+              end
+              chan.on_extended_data do |ch, type, data|
+                cmd.stderr = data
+                cmd.full_stderr += data
+                output << cmd
+              end
+              chan.on_request("exit-status") do |ch, data|
+                exit_status = data.read_long
+              end
+              #chan.on_request("exit-signal") do |ch, data|
+              #  # TODO: This gets called if the program is killed by a signal
+              #  # might also be a worthwhile thing to report
+              #  exit_signal = data.read_string.to_i
+              #  warn ">>> " + exit_signal.inspect
+              #  output << cmd
+              #end
+              chan.on_open_failed do |ch|
+                # TODO: What do do here?
+                # I think we should raise something
+              end
+              chan.on_process do |ch|
+                # TODO: I don't know if this is useful
+              end
+              chan.on_eof do |ch|
+                # TODO: chan sends EOF before the exit status has been
+                # writtend
               end
-              chan.wait
             end
-            ssh.loop
-          end
-          # Set exit_status and log the result upon completion
-          if exit_status
-            cmd.exit_status = exit_status
-            output << cmd
+            chan.wait
           end
+          ssh.loop
+        end
+        # Set exit_status and log the result upon completion
+        if exit_status
+          cmd.exit_status = exit_status
+          output << cmd
         end
       end
 

lib/sshkit/backends/printer.rb

@@ -3,33 +3,12 @@ module Backend
 
     class Printer < Abstract
 
-      include SSHKit::CommandHelper
-
-      def run
-        instance_exec(host, &@block)
-      end
-
-      def execute(*args)
-        command(*args).tap do |cmd|
-          output << cmd
-        end
+      def execute_command(cmd)
+        output << cmd
       end
       alias :upload! :execute
       alias :download! :execute
       alias :test :execute
-
-      def capture(*args)
-        String.new.tap { execute(*args) }
-      end
-      alias :capture! :capture
-
-
-      private
-
-      def output
-        SSHKit.config.output
-      end
-
     end
   end
 end