OTWO-415 First pass at using python library for hg cat

Author: Robin Luckey

.gitignore

@@ -1,3 +1,4 @@
 *.swp
 *.pyc
 pkg/
+*.cache

lib/scm.rb

@@ -16,6 +16,7 @@ module Scm
 require 'lib/scm/adapters/svn_chain_adapter'
 require 'lib/scm/adapters/git_adapter'
 require 'lib/scm/adapters/hg_adapter'
+require 'lib/scm/adapters/hglib_adapter'
 require 'lib/scm/adapters/bzr_adapter'
 require 'lib/scm/adapters/bzrlib_adapter'
 require 'lib/scm/adapters/factory'

lib/scm/adapters/hglib/cat_file.rb

@@ -0,0 +1,9 @@
+module Scm::Adapters
+	class HglibAdapter < HgAdapter
+
+		def cat(revision, path)
+      hg_client.cat_file(revision, path)
+		end
+
+	end
+end

lib/scm/adapters/hglib/client.rb

@@ -0,0 +1,52 @@
+require 'rubygems'
+require 'open4'
+
+class HglibClient
+  def initialize(repository_url)
+    @repository_url = repository_url
+    @py_script = File.dirname(__FILE__) + '/server.py'
+  end
+
+  def start
+    @pid, @stdin, @stdout, @stderr = Open4::popen4 "python #{@py_script}"
+    open_repository
+  end
+
+  def open_repository
+    send_command("REPO_OPEN\t#{@repository_url}")
+  end
+
+  def cat_file(revision, file)
+    send_command("CAT_FILE\t#{revision}\t#{file}")
+  end
+
+  def parent_tokens(revision)
+    send_command("PARENT_TOKENS\t#{revision}").split("\t")
+  end
+
+  def send_command(cmd)
+    # send the command
+    @stdin.puts cmd
+    @stdin.flush
+
+    # get status on stderr, first letter indicates state,
+    # remaing value indicates length of the file content
+    status = @stderr.read(10)
+    flag = status[0,1]
+    size = status[1,9].to_i
+    if flag == 'F'
+      return nil
+    elsif flag == 'E'
+      error = @stdout.read(size)
+      raise RuntimeError.new("Exception in server process\n#{error}")
+    end
+
+    # read content from stdout
+    return @stdout.read(size)
+  end
+
+  def shutdown
+    send_command("QUIT")
+    Process.waitpid(@pid, Process::WNOHANG)
+  end
+end

lib/scm/adapters/hglib/server.py

@@ -0,0 +1,86 @@
+import sys
+import time
+import traceback
+
+from mercurial import ui, hg
+
+class HglibPipeServer:
+  def __init__(self, repository_url):
+    self.ui = ui.ui()
+    self.repository = hg.repository(self.ui, repository_url)
+
+  def get_file_content(self, filename, revision):
+    c = self.repository.changectx(revision)
+    fc = c[filename]
+    contents = fc.data()
+    return contents
+
+  def get_parent_tokens(self, revision):
+    return None
+
+class Command:
+  def __init__(self, line):
+    self.args = line.rstrip().split('\t')
+
+  def get_action(self):
+    return self.args[0]
+
+  def get_arg(self, num):
+    return self.args[num]
+
+def send_status(code, data_len):
+  sys.stderr.write('%s%09d' % (code, data_len))
+  sys.stderr.flush()
+
+def send_success(data_len=0):
+  send_status('T', data_len)
+
+def send_failure(data_len=0):
+  send_status('F', data_len)
+
+def send_error(data_len=0):
+  send_status('E', data_len)
+
+def send_data(result):
+  sys.stdout.write(result)
+  sys.stdout.flush()
+
+def exit_delayed(status, delay=1):
+  time.sleep(delay)
+  sys.exit(status)
+
+def command_loop():
+  while True:
+    cmd = Command(sys.stdin.readline())
+    if cmd.get_action() == 'REPO_OPEN':
+      commander = HglibPipeServer(cmd.get_arg(1))
+      send_success()
+    elif cmd.get_action() == 'CAT_FILE':
+      content = commander.get_file_content(cmd.get_arg(2), cmd.get_arg(1))
+      if content == None:
+        send_failure()
+      else:
+        send_success(len(content))
+        send_data(content)
+    elif cmd.get_action() == 'PARENT_TOKENS':
+      tokens = commander.get_parent_tokens(cmd.get_arg(1))
+      tokens = '|'.join(tokens)
+      send_success(len(tokens))
+      send_data(tokens)
+    elif cmd.get_action() == 'QUIT':
+      send_success()
+      exit_delayed(status=0)
+    else:
+      error = "Invalid Command - %s" % cmd.get_action()
+      send_error(len(error))
+      send_data(error)
+      exit_delayed(status=1)
+
+if __name__ == "__main__":
+  try:
+    command_loop()
+  except:
+    exc_trace = traceback.format_exc()
+    send_error(len(exc_trace))
+    send_data(exc_trace)
+    exit_delayed(status=1)

lib/scm/adapters/hglib_adapter.rb

@@ -0,0 +1,24 @@
+require 'rubygems'
+require 'lib/scm/adapters/hglib/client'
+
+module Scm::Adapters
+	class HglibAdapter < HgAdapter
+
+    def setup
+      hg_client = HglibClient.new(url)
+      hg_client.start
+      hg_client
+    end
+
+    def hg_client
+      @hg_client ||= setup
+    end
+
+    def cleanup
+      @hg_client && @hg_client.shutdown
+    end
+
+	end
+end
+
+require 'lib/scm/adapters/hglib/cat_file'

test/test_helper.rb

@@ -93,6 +93,10 @@ def with_hg_repository(name)
 		with_repository(Scm::Adapters::HgAdapter, name) { |hg| yield hg }
 	end
 
+	def with_hglib_repository(name)
+		with_repository(Scm::Adapters::HglibAdapter, name) { |hg| yield hg }
+	end
+
 	def with_bzr_repository(name)
 		with_repository(Scm::Adapters::BzrAdapter, name) { |bzr| yield bzr }
 	end

test/unit/hglib_cat_file_test.rb

@@ -0,0 +1,47 @@
+require File.dirname(__FILE__) + '/../test_helper'
+
+module Scm::Adapters
+	class HglibCatFileTest < Scm::Test
+
+		def test_cat_file
+			with_hglib_repository('hg') do |hg|
+expected = <<-EXPECTED
+/* Hello, World! */
+
+/*
+ * This file is not covered by any license, especially not
+ * the GNU General Public License (GPL). Have fun!
+ */
+
+#include <stdio.h>
+main()
+{
+	printf("Hello, World!\\n");
+}
+EXPECTED
+
+				# The file was deleted in revision 468336c6671c. Check that it does not exist now, but existed in parent.
+				# assert_equal nil, hg.cat_file(Scm::Commit.new(:token => '75532c1e1f1d'), Scm::Diff.new(:path => 'helloworld.c'))
+				assert_equal expected, hg.cat_file_parent(Scm::Commit.new(:token => '75532c1e1f1d'), Scm::Diff.new(:path => 'helloworld.c'))
+				assert_equal expected, hg.cat_file(Scm::Commit.new(:token => '468336c6671c'), Scm::Diff.new(:path => 'helloworld.c'))
+			end
+		end
+
+		# Ensure that we escape bash-significant characters like ' and & when they appear in the filename
+		def test_funny_file_name_chars
+			Scm::ScratchDir.new do |dir|
+				# Make a file with a problematic filename
+				funny_name = '#|file_name` $(&\'")#'
+				File.open(File.join(dir, funny_name), 'w') { |f| f.write "contents" }
+
+				# Add it to an hg repository
+				`cd #{dir} && hg init && hg add * && hg commit -m test`
+
+				# Confirm that we can read the file back
+				hg = HglibAdapter.new(:url => dir).normalize
+				assert_equal "contents", hg.cat_file(hg.head, Scm::Diff.new(:path => funny_name))
+			end
+		end
+
+	end
+end