[Notes] [Git][BuildStream/buildstream][bst-1.2] 2 commits: _frontend/status.py: Completely remove the blessings dependency from BuildStream

[Tristan Van Berkom <gitlab mg gitlab com>]

Title: GitLab

Tristan Van Berkom pushed to branch bst-1.2 at BuildStream / buildstream

Commits:

• 7ba047b4
  by Tristan Van Berkom at 2018-09-19T09:56:17Z

  _frontend/status.py: Completely remove the blessings dependency from BuildStream
  
  This actually improves reliability of the status bar because we
  now disable it completely in the case that not all of the terminal
  escape sequences are supported on the given terminal.
  
  This replaces the few functions we were using, to move the cursor
  up one line, move it to the beginning of the line, and to clear a
  line, with low level functions provided by the curses module in
  the standard library.
  
  This change makes it easier for downstream distro package maintainers
  to package BuildStream, particularly on Fedora.
  
  Asides from changing _frontend/status.py, this commit includes the
  following changes:
  
    * _frontend/app.py: Use python isatty() function to determine if
                        we are connected to a tty, instead of relying
  		      on blessings.
  
    * setup.py: Remove the dependency on blessings.
  

• c7e5d8be
  by Tristan Van Berkom at 2018-09-19T11:10:22Z

  Merge branch 'tristan/remove-blessings-1.2' into 'bst-1.2'
  
  _frontend/status.py: Completely remove the blessings dependency from BuildStream
  
  See merge request BuildStream/buildstream!809

3 changed files:

• buildstream/_frontend/app.py
• buildstream/_frontend/status.py
• setup.py

Changes:

buildstream/_frontend/app.py

---

...	...	@@ -93,7 +93,7 @@ class App():
93	93	#
94	94	# Earily initialization
95	95	#
96		- is_a_tty = Terminal().is_a_tty
	96	+ is_a_tty = sys.stdout.isatty() and sys.stderr.isatty()
97	97
98	98	# Enable interactive mode if we're attached to a tty
99	99	if main_options['no_interactive']:

buildstream/_frontend/status.py

---

...	...	@@ -16,8 +16,10 @@
16	16	#
17	17	# Authors:
18	18	# Tristan Van Berkom <tristan vanberkom codethink co uk>
	19	+import os
	20	+import sys
19	21	import click
20		-from blessings import Terminal
	22	+import curses
21	23
22	24	# Import a widget internal for formatting time codes
23	25	from .widget import TimeCode
...	...	@@ -43,6 +45,13 @@ from .._scheduler import ElementJob
43	45	#
44	46	class Status():
45	47
	48	+ # Table of the terminal capabilities we require and use
	49	+ _TERM_CAPABILITIES = {
	50	+ 'move_up': 'cuu1',
	51	+ 'move_x': 'hpa',
	52	+ 'clear_eol': 'el'
	53	+ }
	54	+
46	55	def __init__(self, context,
47	56	content_profile, format_profile,
48	57	success_profile, error_profile,
...	...	@@ -56,7 +65,6 @@ class Status():
56	65	self._stream = stream
57	66	self._jobs = []
58	67	self._last_lines = 0 # Number of status lines we last printed to console
59		- self._term = Terminal()
60	68	self._spacing = 1
61	69	self._colors = colors
62	70	self._header = _StatusHeader(context,
...	...	@@ -69,6 +77,7 @@ class Status():
69	77	self._alloc_columns = None
70	78	self._line_length = 0
71	79	self._need_alloc = True
	80	+ self._term_caps = self._init_terminal()
72	81
73	82	# add_job()
74	83	#
...	...	@@ -121,7 +130,7 @@ class Status():
121	130	#
122	131	def clear(self):
123	132
124		- if not self._term.does_styling:
	133	+ if not self._term_caps:
125	134	return
126	135
127	136	for _ in range(self._last_lines):
...	...	@@ -138,7 +147,7 @@ class Status():
138	147	# not necessary to call clear().
139	148	def render(self):
140	149
141		- if not self._term.does_styling:
	150	+ if not self._term_caps:
142	151	return
143	152
144	153	elapsed = self._stream.elapsed_time
...	...	@@ -185,6 +194,55 @@ class Status():
185	194	###################################################
186	195	# Private Methods #
187	196	###################################################
	197	+
	198	+ # _init_terminal()
	199	+ #
	200	+ # Initialize the terminal and return the resolved terminal
	201	+ # capabilities dictionary.
	202	+ #
	203	+ # Returns:
	204	+ # (dict|None): The resolved terminal capabilities dictionary,
	205	+ # or None if the terminal does not support all
	206	+ # of the required capabilities.
	207	+ #
	208	+ def _init_terminal(self):
	209	+
	210	+ # We need both output streams to be connected to a terminal
	211	+ if not (sys.stdout.isatty() and sys.stderr.isatty()):
	212	+ return None
	213	+
	214	+ # Initialized terminal, curses might decide it doesnt
	215	+ # support this terminal
	216	+ try:
	217	+ curses.setupterm(os.environ.get('TERM', 'dumb'))
	218	+ except curses.error:
	219	+ return None
	220	+
	221	+ term_caps = {}
	222	+
	223	+ # Resolve the string capabilities we need for the capability
	224	+ # names we need.
	225	+ #
	226	+ for capname, capval in self._TERM_CAPABILITIES.items():
	227	+ code = curses.tigetstr(capval)
	228	+
	229	+ # If any of the required capabilities resolve empty strings or None,
	230	+ # then we don't have the capabilities we need for a status bar on
	231	+ # this terminal.
	232	+ if not code:
	233	+ return None
	234	+
	235	+ # Decode sequences as latin1, as they are always 8-bit bytes,
	236	+ # so when b'\xff' is returned, this must be decoded to u'\xff'.
	237	+ #
	238	+ # This technique is employed by the python blessings library
	239	+ # as well, and should provide better compatibility with most
	240	+ # terminals.
	241	+ #
	242	+ term_caps[capname] = code.decode('latin1')
	243	+
	244	+ return term_caps
	245	+
188	246	def _check_term_width(self):
189	247	term_width, _ = click.get_terminal_size()
190	248	if self._term_width != term_width:
...	...	@@ -192,12 +250,24 @@ class Status():
192	250	self._need_alloc = True
193	251
194	252	def _move_up(self):
	253	+ assert self._term_caps is not None
	254	+
195	255	# Explicitly move to beginning of line, fixes things up
196	256	# when there was a ^C or ^Z printed to the terminal.
197		- click.echo(self._term.move_x(0) + self._term.move_up, nl=False, err=True)
	257	+ move_x = curses.tparm(self._term_caps['move_x'].encode('latin1'), 0)
	258	+ move_x = move_x.decode('latin1')
	259	+
	260	+ move_up = curses.tparm(self._term_caps['move_up'].encode('latin1'))
	261	+ move_up = move_up.decode('latin1')
	262	+
	263	+ click.echo(move_x + move_up, nl=False, err=True)
198	264
199	265	def _clear_line(self):
200		- click.echo(self._term.clear_eol, nl=False, err=True)
	266	+ assert self._term_caps is not None
	267	+
	268	+ clear_eol = curses.tparm(self._term_caps['clear_eol'].encode('latin1'))
	269	+ clear_eol = clear_eol.decode('latin1')
	270	+ click.echo(clear_eol, nl=False, err=True)
201	271
202	272	def _allocate(self):
203	273	if not self._need_alloc:

setup.py

---

...	...	@@ -297,7 +297,6 @@ setup(name='BuildStream',
297	297	'ruamel.yaml < 0.15.52',
298	298	'pluginbase',
299	299	'Click',
300		- 'blessings >= 1.6',
301	300	'jinja2 >= 2.10',
302	301	'protobuf >= 3.5',
303	302	'grpcio >= 1.10',

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