initial import

The original osmo-gsm-tester was an internal development at sysmocom, mostly by
D. Laszlo Sitzer <dlsitzer@sysmocom.de>, of which this public osmo-gsm-tester
is a refactoring / rewrite.

This imports an early state of the refactoring and is not functional yet. Bits
from the earlier osmo-gsm-tester will be added as needed. The earlier commit
history is not imported.
diff --git a/src/osmo_gsm_tester/log.py b/src/osmo_gsm_tester/log.py
new file mode 100644
index 0000000..27194a9
--- /dev/null
+++ b/src/osmo_gsm_tester/log.py
@@ -0,0 +1,405 @@
+# osmo_gsm_tester: global logging
+#
+# Copyright (C) 2016-2017 by sysmocom - s.f.m.c. GmbH
+#
+# Author: Neels Hofmeyr <neels@hofmeyr.de>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import sys
+import time
+import traceback
+import contextlib
+from inspect import getframeinfo, stack
+
+L_ERR = 30
+L_LOG = 20
+L_DBG = 10
+L_TRACEBACK = 'TRACEBACK'
+
+C_NET = 'net'
+C_RUN = 'run'
+C_TST = 'tst'
+C_CNF = 'cnf'
+C_DEFAULT = '---'
+
+LONG_DATEFMT = '%Y-%m-%d_%H:%M:%S'
+DATEFMT = '%H:%M:%S'
+
+class LogTarget:
+    do_log_time = None
+    do_log_category = None
+    do_log_level = None
+    do_log_origin = None
+    do_log_traceback = None
+    do_log_src = None
+    origin_width = None
+    origin_fmt = None
+
+    # redirected by logging test
+    get_time_str = lambda self: time.strftime(self.log_time_fmt)
+
+    # sink that gets each complete logging line
+    log_sink = sys.stderr.write
+
+    category_levels = None
+
+    def __init__(self):
+        self.category_levels = {}
+        self.style()
+
+    def style(self, time=True, time_fmt=DATEFMT, category=True, level=True, origin=True, origin_width=0, src=True, trace=False):
+        '''
+        set all logging format aspects, to defaults if not passed:
+        time: log timestamps;
+        time_fmt: format of timestamps;
+        category: print the logging category (three letters);
+        level: print the logging level, unless it is L_LOG;
+        origin: print which object(s) the message originated from;
+        origin_width: fill up the origin string with whitespace to this witdh;
+        src: log the source file and line number the log comes from;
+        trace: on exceptions, log the full stack trace;
+        '''
+        self.log_time_fmt = time_fmt
+        self.do_log_time = bool(time)
+        if not self.log_time_fmt:
+            self.do_log_time = False
+        self.do_log_category = bool(category)
+        self.do_log_level = bool(level)
+        self.do_log_origin = bool(origin)
+        self.origin_width = int(origin_width)
+        self.origin_fmt = '{:>%ds}' % self.origin_width
+        self.do_log_src = src
+        self.do_log_traceback = trace
+
+    def style_change(self, time=None, time_fmt=None, category=None, level=None, origin=None, origin_width=None, src=None, trace=None):
+        'modify only the given aspects of the logging format'
+        self.style(
+            time=(time if time is not None else self.do_log_time),
+            time_fmt=(time_fmt if time_fmt is not None else self.log_time_fmt),
+            category=(category if category is not None else self.do_log_category),
+            level=(level if level is not None else self.do_log_level),
+            origin=(origin if origin is not None else self.do_log_origin),
+            origin_width=(origin_width if origin_width is not None else self.origin_width),
+            src=(src if src is not None else self.do_log_src),
+            trace=(trace if trace is not None else self.do_log_traceback),
+            )
+
+    def set_level(self, category, level):
+        'set global logging log.L_* level for a given log.C_* category'
+        self.category_levels[category] = level
+
+    def is_enabled(self, category, level):
+        if level == L_TRACEBACK:
+            return self.do_log_traceback
+        is_level = self.category_levels.get(category)
+        if is_level is None:
+            is_level = L_LOG
+        if level < is_level:
+            return False
+        return True
+
+    def log(self, origin, category, level, src, messages, named_items):
+        if category and len(category) != 3:
+            self.log_sink('WARNING: INVALID LOG SUBSYSTEM %r\n' % category)
+            self.log_sink('origin=%r category=%r level=%r\n' % (origin, category, level));
+
+        if not category:
+            category = C_DEFAULT
+        if not self.is_enabled(category, level):
+            return
+
+        log_pre = []
+        if self.do_log_time:
+            log_pre.append(self.get_time_str())
+
+        if self.do_log_category:
+            log_pre.append(category)
+
+        if self.do_log_origin:
+            if origin is None:
+                name = '-'
+            elif isinstance(origin, str):
+                name = origin or None
+            elif hasattr(origin, '_name'):
+                name = origin._name
+            if not name:
+                name = str(origin.__class__.__name__)
+            log_pre.append(self.origin_fmt.format(name))
+
+        if self.do_log_level and level != L_LOG:
+            log_pre.append(level_str(level) or ('loglevel=' + str(level)) )
+
+        log_line = [str(m) for m in messages]
+
+        if named_items:
+            # unfortunately needs to be sorted to get deterministic results
+            log_line.append('{%s}' %
+                            (', '.join(['%s=%r' % (k,v)
+                             for k,v in sorted(named_items.items())])))
+
+        if self.do_log_src and src:
+            log_line.append(' [%s]' % str(src))
+
+        log_str = '%s%s%s' % (' '.join(log_pre),
+                              ': ' if log_pre else '',
+                              ' '.join(log_line))
+
+        self.log_sink(log_str.strip() + '\n')
+
+
+targets = [ LogTarget() ]
+
+def level_str(level):
+    if level == L_TRACEBACK:
+        return L_TRACEBACK
+    if level <= L_DBG:
+        return 'DBG'
+    if level <= L_LOG:
+        return 'LOG'
+    return 'ERR'
+
+def _log_all_targets(origin, category, level, src, messages, named_items=None):
+    global targets
+    if isinstance(src, int):
+        src = get_src_from_caller(src + 1)
+    for target in targets:
+        target.log(origin, category, level, src, messages, named_items)
+
+def get_src_from_caller(levels_up=1):
+    caller = getframeinfo(stack()[levels_up][0])
+    return '%s:%d' % (os.path.basename(caller.filename), caller.lineno)
+
+def get_src_from_tb(tb, levels_up=1):
+    ftb = traceback.extract_tb(tb)
+    f,l,m,c = ftb[-levels_up]
+    f = os.path.basename(f)
+    return '%s:%s: %s' % (f, l, c)
+
+
+class Origin:
+    '''
+    Base class for all classes that want to log,
+    and to add an origin string to a code path:
+    with log.Origin('my name'):
+        raise Problem()
+    This will log 'my name' as an origin for the Problem.
+    '''
+
+    _log_category = None
+    _src = None
+    _name = None
+    _log_line_buf = None
+    _prev_stdout = None
+
+    _global_current_origin = None
+    _parent_origin = None
+
+    def __init__(self, *name_items, category=None, **detail_items):
+        self.set_log_category(category)
+        self.set_name(*name_items, **detail_items)
+
+    def set_name(self, *name_items, **detail_items):
+        if name_items:
+            name = '-'.join([str(i) for i in name_items])
+        elif not detail_items:
+            name = self.__class__.__name__
+        else:
+            name = ''
+        if detail_items:
+            details = '(%s)' % (', '.join([("%s=%r" % (k,v))
+                                           for k,v in sorted(detail_items.items())]))
+        else:
+            details = ''
+        self._name = name + details
+
+    def name(self):
+        return self._name
+
+    def set_log_category(self, category):
+        self._log_category = category
+
+    def _log(self, level, messages, named_items=None, src_levels_up=3, origins=None):
+        src = self._src or src_levels_up
+        origin = origins or self.gather_origins()
+        _log_all_targets(origin, self._log_category, level, src, messages, named_items)
+
+    def dbg(self, *messages, **named_items):
+        self._log(L_DBG, messages, named_items)
+
+    def log(self, *messages, **named_items):
+        self._log(L_LOG, messages, named_items)
+
+    def err(self, *messages, **named_items):
+        self._log(L_ERR, messages, named_items)
+
+    def log_exn(self, exc_info=None):
+        log_exn(self, self._log_category, exc_info)
+
+    def __enter__(self):
+        if self._parent_origin is not None:
+            return
+        if Origin._global_current_origin == self:
+            return
+        self._parent_origin, Origin._global_current_origin = Origin._global_current_origin, self
+
+    def __exit__(self, *exc_info):
+        rc = None
+        if exc_info[0] is not None:
+            rc = exn_add_info(exc_info, self)
+        Origin._global_current_origin, self._parent_origin = self._parent_origin, None
+        return rc
+
+    def redirect_stdout(self):
+        return contextlib.redirect_stdout(self)
+
+    def write(self, message):
+        'to redirect stdout to the log'
+        lines = message.splitlines()
+        if not lines:
+            return
+        if self._log_line_buf:
+            lines[0] = self._log_line_buf + lines[0]
+            self._log_line_buf = None
+        if not message.endswith('\n'):
+            self._log_line_buf = lines[-1]
+            lines = lines[:-1]
+        origins = self.gather_origins()
+        for line in lines:
+            self._log(L_LOG, (line,), origins=origins)
+
+    def flush(self):
+        pass
+
+    def gather_origins(self):
+        origins = Origins()
+        origin = self
+        while origin:
+            origins.add(origin)
+            origin = origin._parent_origin
+        return str(origins)
+
+
+
+def dbg(origin, category, *messages, **named_items):
+    _log_all_targets(origin, category, L_DBG, 2, messages, named_items)
+
+def log(origin, category, *messages, **named_items):
+    _log_all_targets(origin, category, L_LOG, 2, messages, named_items)
+
+def err(origin, category, *messages, **named_items):
+    _log_all_targets(origin, category, L_ERR, 2, messages, named_items)
+
+def trace(origin, category, exc_info):
+    _log_all_targets(origin, category, L_TRACEBACK, None,
+                     traceback.format_exception(*exc_info))
+
+def resolve_category(origin, category):
+    if category is not None:
+        return category
+    if not hasattr(origin, '_log_category'):
+        return None
+    return origin._log_category
+
+def exn_add_info(exc_info, origin, category=None):
+    etype, exception, tb = exc_info
+    if not hasattr(exception, 'origins'):
+        exception.origins = Origins()
+    if not hasattr(exception, 'category'):
+        # only remember the deepest category
+        exception.category = resolve_category(origin, category)
+    if not hasattr(exception, 'src'):
+        exception.src = get_src_from_tb(tb)
+    exception.origins.add(origin)
+    return False
+
+
+
+def log_exn(origin=None, category=None, exc_info=None):
+    if not (exc_info is not None and len(exc_info) == 3):
+        exc_info = sys.exc_info()
+        if not (exc_info is not None and len(exc_info) == 3):
+            raise RuntimeError('invalid call to log_exn() -- no valid exception info')
+
+    etype, exception, tb = exc_info
+
+    # if there are origins recorded with the Exception, prefer that
+    if hasattr(exception, 'origins'):
+        origin = str(exception.origins)
+
+    # if there is a category recorded with the Exception, prefer that
+    if hasattr(exception, 'category'):
+        category = exception.category
+
+    if hasattr(exception, 'msg'):
+        msg = exception.msg
+    else:
+        msg = str(exception)
+
+    if hasattr(exception, 'src'):
+        src = exception.src
+    else:
+        src = 2
+
+    trace(origin, category, exc_info)
+    _log_all_targets(origin, category, L_ERR, src,
+                     ('%s:' % str(etype.__name__), msg))
+
+
+class Origins(list):
+    def __init__(self, origin=None):
+        if origin is not None:
+            self.add(origin)
+    def add(self, origin):
+        if hasattr(origin, '_name'):
+            origin_str = origin._name
+        else:
+            origin_str = str(origin)
+        self.insert(0, origin_str)
+    def __str__(self):
+        return '->'.join(self)
+
+
+
+def set_level(category, level):
+    global targets
+    for target in targets:
+        target.set_level(category, level)
+
+def style(**kwargs):
+    global targets
+    for target in targets:
+        target.style(**kwargs)
+
+def style_change(**kwargs):
+    global targets
+    for target in targets:
+        target.style_change(**kwargs)
+
+class TestsTarget(LogTarget):
+    'LogTarget producing deterministic results for regression tests'
+    def __init__(self, out=sys.stdout):
+        super().__init__()
+        self.style(time=False, src=False)
+        self.log_sink = out.write
+
+def run_logging_exceptions(func, *func_args, return_on_failure=None, **func_kwargs):
+    try:
+        return func(*func_args, **func_kwargs)
+    except:
+        log_exn()
+        return return_on_failure
+
+# vim: expandtab tabstop=4 shiftwidth=4