# Copyright 2023-2024 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Check that the $_inferior_thread_count convenience variable will
# correctly update its value without passing through a normal stop
# event.
#
# When GDB is using a remote (or extended-remote) target, GDB only
# learns about changes to the thread list be explicitly querying the
# target.  This is done as part of a normal stop, but there are some
# situations where the thread list can change, but GDB doesn't pass
# through a normal stop.
#
# For example, when the target is running asynchronously in non-stop
# mode; in this case GDB can query the thread list without the target
# ever stopping.
#
# Or after an inferior function call.
#
# The solution is to ensure that $_inferior_thread_count explicitly
# queries the target to update the thread list.  This test checks that
# this is done.

standard_testfile

if {[build_executable "failed to prepare" $testfile $srcfile \
	 {debug pthreads}] == -1} {
    return -1
}

# Start GDB.  Ensure we are in non-stop mode as we need to read from
# the inferior while it is running.
save_vars {GDBFLAGS} {
    append GDBFLAGS " -ex \"set non-stop on\""
    clean_restart $binfile
}

if ![runto_main] {
    return -1
}

gdb_breakpoint breakpt
gdb_continue_to_breakpoint "first breakpt call"

# Check we can see a single thread to begin with.
gdb_test "p \$_inferior_thread_count" \
    "^\\\$$::decimal = 1" \
    "only one thread in \$_inferior_thread_count"

# We don't want thread events, it makes it harder to match GDB's
# output.
gdb_test_no_output "set print thread-events off"

# Continue the program in the background.
set test "continue&"
gdb_test_multiple "continue&" $test {
    -re "Continuing\\.\r\n$gdb_prompt " {
	pass $test
    }
}

# Read the 'stage' flag from the inferior.  This is initially 0, but
# will be set to 1 once the extra thread has been created, and then 2
# once the extra thread has exited.
#
# We catch the case where we can't read from the inferior while the
# inferior is running, this happens if the target hasn't entered
# non-stop mode like we asked.  In this case we interrupt the inferior
# and bail.
#
# Otherwise, if we can read from the inferior we try at most 10 times
# to read the flag (with a 1 second delay after each read).  If the
# flag isn't set after this then we bail.  The inferior is either very
# slow, or the thread hasn't started for some reason.
proc wait_for_stage { num } {
    set failure_count 0
    set cmd "print /d stage"
    set stage_flag 0
    gdb_test_multiple "$cmd" "wait for 'stage' flag to be $num" {
	-re -wrap "^Cannot execute this command while the target is running\\.\r\nUse the \"interrupt\" command to stop the target\r\nand then try again\\." {
	    fail "$gdb_test_name (can't read asynchronously)"
	    gdb_test_no_output "interrupt"

	    gdb_test_multiple "" "wait for thread to stop" {
		-re "Thread .* received signal .*" {
		    pass $gdb_test_name
		    gdb_test "p 1 + 2" " = 3"
		}
	    }
	}

	-re -wrap "^\\$\[0-9\]* = (\[-\]*\[0-9\]*).*" {
	    set stage_flag $expect_out(1,string)
	    if {$stage_flag != $num} {
		set stage_flag 0
		incr failure_count
		if { $failure_count < 10 } {
		    sleep 1
		    send_gdb "$cmd\n"
		    exp_continue
		}
		fail $gdb_test_name
	    } else {
		pass $gdb_test_name
	    }
	}
    }

    return $stage_flag
}

# Wait until we can see that the extra thread has been created.
if {![wait_for_stage 1]} {
    unresolved "failed to see thread start"
    return -1
}


if {[target_info exists gdb_protocol]
    && ([target_info gdb_protocol] == "remote"
	|| [target_info gdb_protocol] == "extended-remote")} {
    set new_thread_re "\\\[New Thread \[^\r\n\]+\\\]\r\n"
    set exit_thread_re "\\\[Thread \[^\r\n\]+ exited\\\]\r\n"
} else {
    set new_thread_re ""
    set exit_thread_re ""
}

# This is the test we actually care about.  Check that the
# $_inferior_thread_count convenience variable shows the correct
# thread count; the new thread should be visible.
gdb_test "with print thread-events on -- p \$_inferior_thread_count" \
    "^${new_thread_re}\\\$$::decimal = 2" \
    "second thread visible in \$_inferior_thread_count"

# Set a variable in the inferior, this will cause the second thread to
# exit.
gdb_test_no_output "set variable spin = 0" \
    "set 'spin' flag to allow worker thread to exit"

# Wait until the extra thread has exited.
if {![wait_for_stage 2]} {
    unresolved "failed to see thread start"
    return -1
}

# Check that the second thread has gone away.
gdb_test "with print thread-events on -- p \$_inferior_thread_count" \
    "^${exit_thread_re}\\\$$::decimal = 1" \
    "back to one thread visible in \$_inferior_thread_count"

# Set a variable in the inferior, this will cause the second thread to
# exit.
gdb_test_no_output "set variable spin = 0" \
    "set 'spin' flag to allow main thread to exit"

# When the second thread exits, the main thread joins with it, and
# then proceeds to hit the breakpt function again.
gdb_test_multiple "" "wait for main thread to stop" {
    -re "Thread 1 \[^\r\n\]+ hit Breakpoint $decimal, breakpt \\(\\)\[^\r\n\]+\r\n\[^\r\n\]+\r\n" {
	pass $gdb_test_name
    }
}