def reverse_watch(dbg, s_expr):
"""Perform 'reverse-watch' command on expression.
'dbg' is the instance of ReversibleDebugger on which to operate."""
s_expr_val = dbg.evaluate_expression(s_expr)
fredutil.fred_debug("RW: Starting with expr value '%s'" % s_expr_val)
# Find starting checkpoint using binary search:
binary_search._binary_search_checkpoints(dbg, s_expr, s_expr_val)
# STILL TESTING: When "else" branch works well, it will become permanent,
# and the remaining branch of "if" can be removed.
if False:
dbg.current_checkpoint().set_history(
binary_search._binary_search_history(dbg,
dbg.copy_current_checkpoint_history(),
0, s_expr, s_expr_val))
else:
if dbg.branch.get_num_checkpoints() == 0:
fredutil.fred_error("No checkpoints found for reverse-watch.")
return
l_history_copy = dbg.copy_current_checkpoint_history()
try:
dbg.current_checkpoint().set_history(
binary_search.NEW_binary_search_since_last_checkpoint(dbg, l_history_copy,
0, s_expr, s_expr_val))
except binary_search.BinarySearchTooFarAtStartError:
fredutil.fred_debug("BinarySearchTooFarAtStartError handled")
fredutil.fred_info(
'reverse-watch failed; expr "%s"\n is same at start and end.'
% s_expr )
dbg.update_state()
fredutil.fred_debug("Reverse watch finished.")
def reverse_watch(dbg, s_expr):
"""Perform 'reverse-watch' command on expression.
'dbg' is the instance of ReversibleDebugger on which to operate."""
s_expr_val = dbg.evaluate_expression(s_expr)
fredutil.fred_debug("RW: Starting with expr value '%s'" % s_expr_val)
# Find starting checkpoint using binary search:
binary_search._binary_search_checkpoints(dbg, s_expr, s_expr_val)
# STILL TESTING: When "else" branch works well, it will become permanent,
# and the remaining branch of "if" can be removed.
if False:
dbg.current_checkpoint().set_history(
binary_search._binary_search_history(
dbg, dbg.copy_current_checkpoint_history(), 0, s_expr,
s_expr_val))
else:
if dbg.branch.get_num_checkpoints() == 0:
fredutil.fred_error("No checkpoints found for reverse-watch.")
return
l_history_copy = dbg.copy_current_checkpoint_history()
try:
dbg.current_checkpoint().set_history(
binary_search.NEW_binary_search_since_last_checkpoint(
dbg, l_history_copy, 0, s_expr, s_expr_val))
except binary_search.BinarySearchTooFarAtStartError:
fredutil.fred_debug("BinarySearchTooFarAtStartError handled")
fredutil.fred_info(
'reverse-watch failed; expr "%s"\n is same at start and end.'
% s_expr)
dbg.update_state()
fredutil.fred_debug("Reverse watch finished.")
def reverse_watch_with_log_support(dbg, s_expr):
"""Perform 'reverse-watch' with support from fred_command."""
s_expr_val = dbg.evaluate_expression(s_expr)
fredutil.fred_debug("RW: Starting with expr value '%s'" % s_expr_val)
# Find starting checkpoint using binary search:
binary_search._binary_search_checkpoints(dbg, s_expr, s_expr_val)
dbg.current_checkpoint().set_history(
binary_search._binary_search_with_log(dbg, s_expr, s_expr_val))
dbg.update_state()
fredutil.fred_debug("Reverse watch finished.")
def reverse_watch_for_mt(dbg, s_expr):
"""Perform 'reverse-watch' command on expression, with support for
an expression changing in a thread which is not the main thread."""
fredutil.fred_timer_start("reverse-watch")
if dbg.branch.get_num_checkpoints() == 0:
fredutil.fred_error("No checkpoints found for reverse-watch.")
return
s_expr_val = dbg.evaluate_expression(s_expr)
testIfTooFar = lambda: dbg.test_expression(s_expr, s_expr_val)
fredutil.fred_debug("RW: Starting with expr value '%s'" % s_expr_val)
# ---------------------------- Binary search of checkpoints
if dbg.branch.get_num_checkpoints() > 1:
# Find starting checkpoint using binary search:
binary_search._binary_search_checkpoints(dbg, s_expr, s_expr_val)
# ---------------------------- Binary search on the main thread
if _reverse_watch_main_thread(dbg, s_expr, s_expr_val):
fredutil.fred_debug("Main thread changed expression.")
fredutil.fred_debug("Reverse-watch finished.")
fredutil.fred_assert(not testIfTooFar())
return
# If we're here, it means a secondary thread caused expr to change.
fredutil.fred_debug("Secondary thread caused expr to change. "
"Starting binary search of system calls.")
# ---------------------------- Binary search through system calls
binary_search.binary_search_log_events(dbg, testIfTooFar)
# We are now at a point in time where at some point after the next
# system call the expression will change. We are guaranteed that
# the culprit thread is alive, because a "pthread_create" call is
# an event in the system call log, and the binary search will
# consider that in determining the lower bound.
# ---------------------------- Round-robin search for culprit thread
if not _reverse_watch_round_robin(dbg, testIfTooFar):
fredutil.fred_error("Reverse-watch failed to determine the thread "
"which caused the expression '%s' to change." %
s_expr)
return
# At this point, whatever thread we are currently in is the correct thread.
fredutil.fred_debug("Identified thread %d as the one changing expr." %
dbg.get_current_thread())
fredutil.fred_assert(not testIfTooFar())
dbg.current_checkpoint().set_history(
binary_search._binary_search_regular_next_expansion(dbg, testIfTooFar))
dbg.update_state()
fredutil.fred_assert(not testIfTooFar())
fredutil.fred_debug("Reverse watch finished.")
fredutil.fred_timer_stop("reverse-watch")
dbg.report_timing_statistics()
return
