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1# Copyright 2018, The Android Open Source Project
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#     http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14
15#
16# !!! Keep up-to-date with var_cache.sh
17#
18
19#
20# Provide a soong-build variable query mechanism that is cached
21# in the current process and any other subchild process that knows
22# how to parse the exported variable:
23#
24# export ART_TOOLS_BUILD_VAR_CACHE="..."
25#
26# Of the format:
27#
28#   <key1>='<value1>'\n
29#   <key2>='<value2>'\n
30#   ...
31#   <keyN>='<valueN>'
32#
33# Note: This is intentionally the same output format as
34#     build/soong/soong_ui.bash --dumpvars-mode --vars "key1 key2 ... keyN"
35#
36# For example, this would be a valid var-cache:
37#
38# export ART_TOOLS_BUILD_VAR_CACHE="TARGET_CORE_JARS='core-oj core-libart'
39#   HOST_CORE_JARS='core-oj-hostdex core-libart-hostdex'"
40#
41# Calling into soong repeatedly is very slow; whenever it needs to be done
42# more than once, the var_cache.py or var_cache.sh script should be used instead.
43#
44
45import os
46import subprocess
47import sys
48
49def get_build_var(name):
50  """
51  Query soong build for a variable value and return it as a string.
52
53  Var lookup is cached, subsequent var lookups in any child process
54  (that includes a var-cache is free). The var must be in 'var_list'
55  to participate in the cache.
56
57  Example:
58     host_out = var_cache.get_build_var('HOST_OUT')
59
60  Note that build vars can often have spaces in them,
61  so the caller must take care to ensure space-correctness.
62
63  Raises KeyError if the variable name is not in 'var_list'.
64  """
65  _populate()
66  _build_dict()
67
68  value = _var_cache_dict.get(name)
69  if value is None:
70    _debug(_var_cache_dict)
71    raise KeyError("The variable '%s' is not in 'var_list', can't lookup" %(name))
72
73  return value
74
75_var_cache_dict = None
76_THIS_DIR = os.path.dirname(os.path.realpath(__file__))
77_TOP = os.path.join(_THIS_DIR, "../../..")
78_VAR_LIST_PATH = os.path.join(_THIS_DIR, "var_list")
79_SOONG_UI_SCRIPT = os.path.join(_TOP, "build/soong/soong_ui.bash")
80_DEBUG = False
81
82def _populate():
83  if os.environ.get('ART_TOOLS_BUILD_VAR_CACHE'):
84    return
85
86  _debug("Varcache missing (PY)... repopulate")
87
88  interesting_vars=[]
89  with open(_VAR_LIST_PATH) as f:
90    for line in f.readlines():
91      line = line.strip()
92      if not line or line.startswith('#'):
93        continue
94
95      _debug(line)
96
97      interesting_vars.append(line)
98
99  _debug("Interesting vars: ", interesting_vars)
100
101  # Invoke soong exactly once for optimal performance.
102  var_values = subprocess.check_output([
103      _SOONG_UI_SCRIPT, '--dumpvars-mode', '-vars', " ".join(interesting_vars)],
104      cwd=_TOP)
105
106  # Export the ART_TOOLS_BUILD_VAR_CACHE in the same format as soong_ui.bash --dumpvars-mode.
107  os.environb[b'ART_TOOLS_BUILD_VAR_CACHE'] = var_values
108
109  _debug("Soong output: ", var_values)
110
111def _build_dict():
112  global _var_cache_dict
113
114  if _var_cache_dict:
115    return
116
117  _debug("_var_cache_build_dict()")
118
119  _var_cache_dict = {}
120
121  # Parse $ART_TOOLS_BUILD_VAR_CACHE, e.g.
122  #   TARGET_CORE_JARS='core-oj core-libart conscrypt okhttp bouncycastle apache-xml'
123  #   HOST_CORE_JARS='core-oj-hostdex core-libart-hostdex ...'
124
125  for line in os.environ['ART_TOOLS_BUILD_VAR_CACHE'].splitlines():
126    _debug(line)
127    var_name, var_value = line.split("=")
128    var_value = var_value.strip("'")
129
130    _debug("Var name =", var_name)
131    _debug("Var value =", var_value)
132
133    _var_cache_dict[var_name] = var_value
134
135  _debug("Num entries in dict: ", len(_var_cache_dict))
136
137def _debug(*args):
138  if _DEBUG:
139    print(*args, file=sys.stderr)
140
141# Below definitions are for interactive use only, e.g.
142# python -c 'import var_cache; var_cache._dump_cache()'
143
144def _dump_cache():
145  _populate()
146  print(os.environ['ART_TOOLS_BUILD_VAR_CACHE'])
147
148#get_build_var("xyz")
149