python/demo/main.py

# Copyright 2012 Google Inc. All Rights Reserved.

#[START sample]
"""A sample app that uses GCS client to operate on bucket and file."""

#[START imports]
import logging
import os
import cloudstorage as gcs
import webapp2

from google.appengine.api import app_identity
#[END imports]

#[START retries]
my_default_retry_params = gcs.RetryParams(initial_delay=0.2,
                                          max_delay=5.0,
                                          backoff_factor=2,
                                          max_retry_period=15)
gcs.set_default_retry_params(my_default_retry_params)
#[END retries]


class MainPage(webapp2.RequestHandler):
  """Main page for GCS demo application."""

#[START get_default_bucket]
  def get(self):
    bucket_name = os.environ.get('BUCKET_NAME',
                                 app_identity.get_default_gcs_bucket_name())

    self.response.headers['Content-Type'] = 'text/plain'
    self.response.write('Demo GCS Application running from Version: '
                        + os.environ['CURRENT_VERSION_ID'] + '\n')
    self.response.write('Using bucket name: ' + bucket_name + '\n\n')
#[END get_default_bucket]

    bucket = '/' + bucket_name
    filename = bucket + '/demo-testfile'
    self.tmp_filenames_to_clean_up = []

    try:
      self.create_file(filename)
      self.response.write('\n\n')

      self.read_partial_file(filename)
      self.response.write('\n\n')
      
      self.read_file(filename)
      self.response.write('\n\n')

      self.stat_file(filename)
      self.response.write('\n\n')

      self.create_files_for_list_bucket(bucket)
      self.response.write('\n\n')

      self.list_bucket(bucket)
      self.response.write('\n\n')

      self.list_bucket_directory_mode(bucket)
      self.response.write('\n\n')

    except Exception, e:
      logging.exception(e)
      self.delete_files()
      self.response.write('\n\nThere was an error running the demo! '
                          'Please check the logs for more details.\n')

    else:
      self.delete_files()
      self.response.write('\n\nThe demo ran successfully!\n')

#[START write]
  def create_file(self, filename):
    """Create a file.

    The retry_params specified in the open call will override the default
    retry params for this particular file handle.

    Args:
      filename: filename.
    """
    self.response.write('Creating file %s\n' % filename)

    write_retry_params = gcs.RetryParams(backoff_factor=1.1)
    gcs_file = gcs.open(filename,
                        'w',
                        content_type='text/plain',
                        options={'x-goog-meta-foo': 'foo',
                                 'x-goog-meta-bar': 'bar'},
                        retry_params=write_retry_params)
    gcs_file.write('abcde\n')
    gcs_file.write('f'*1024*4 + '\n')
    gcs_file.close()
    self.tmp_filenames_to_clean_up.append(filename)
#[END write]
#[START read_partial]
  def read_partial_file(self, filename):
    self.response.write('Abbreviated file content (first line and last 1K):\n')

    gcs_file = gcs.open(filename)
    self.response.write(gcs_file.readline())
    gcs_file.seek(-1024, os.SEEK_END)
    self.response.write(gcs_file.read())
    gcs_file.close()
#[END read_partial]

#[START read]
  def read_file(self, filename):
    self.response.write('Reading the full file contents:\n')
    
    gcs_file = gcs.open(filename)
    contents = gcs_file.read()
    gcs_file.close()
    self.response.write(contents)
#[END read]

  def stat_file(self, filename):
    self.response.write('File stat:\n')

    stat = gcs.stat(filename)
    self.response.write(repr(stat))

  def create_files_for_list_bucket(self, bucket):
    self.response.write('Creating more files for listbucket...\n')
    filenames = [bucket + n for n in ['/foo1', '/foo2', '/bar', '/bar/1',
                                      '/bar/2', '/boo/']]
    for f in filenames:
      self.create_file(f)

#[START list_bucket]
  def list_bucket(self, bucket):
    """Create several files and paginate through them.

    Production apps should set page_size to a practical value.

    Args:
      bucket: bucket.
    """
    self.response.write('Listbucket result:\n')

    page_size = 1
    stats = gcs.listbucket(bucket + '/foo', max_keys=page_size)
    while True:
      count = 0
      for stat in stats:
        count += 1
        self.response.write(repr(stat))
        self.response.write('\n')

      if count != page_size or count == 0:
        break
      stats = gcs.listbucket(bucket + '/foo', max_keys=page_size,
                             marker=stat.filename)
#[END list_bucket]

  def list_bucket_directory_mode(self, bucket):
    self.response.write('Listbucket directory mode result:\n')
    for stat in gcs.listbucket(bucket + '/b', delimiter='/'):
      self.response.write('%r' % stat)
      self.response.write('\n')
      if stat.is_dir:
        for subdir_file in gcs.listbucket(stat.filename, delimiter='/'):
          self.response.write('  %r' % subdir_file)
          self.response.write('\n')

#[START delete_files]
  def delete_files(self):
    self.response.write('Deleting files...\n')
    for filename in self.tmp_filenames_to_clean_up:
      self.response.write('Deleting file %s\n' % filename)
      try:
        gcs.delete(filename)
      except gcs.NotFoundError:
        pass
#[END delete_files]


app = webapp2.WSGIApplication([('/', MainPage)],
                              debug=True)
#[END sample]