Add new_inferior, inferior_deleted, and new_thread events

This adds a few new events to gdb's Python layer: new_inferior,
inferior_deleted, and new_thread.  I wanted to be able to add a
combined inferior/thread display window to my GUI, and I needed a few
events to make this work.  This is PR python/15622.

ChangeLog
2017-09-11  Tom Tromey  <tom@tromey.com>

	PR python/15622:
	* NEWS: Add entry.
	* python/python.c (do_start_initialization): Initialize new event
	types.
	* python/python-internal.h (gdbpy_initialize_new_inferior_event)
	(gdbpy_initialize_inferior_deleted_event)
	(gdbpy_initialize_new_thread_event): Declare.
	* python/py-threadevent.c (create_thread_event_object): Add option
	"thread" parameter.
	* python/py-inferior.c (new_thread_event_object_type)
	(new_inferior_event_object_type)
	(inferior_deleted_event_object_type): Declare.
	(python_new_inferior, python_inferior_deleted): New functions.
	(add_thread_object): Emit new_thread event.
	(gdbpy_initialize_inferior): Attach new functions to corresponding
	observers.
	(new_thread, new_inferior, inferior_deleted): Define new event
	types.
	* python/py-evts.c (gdbpy_initialize_py_events): Add new
	registries.
	* python/py-events.h (events_object) <new_inferior,
	inferior_deleted, new_thread>: New fields.
	* python/py-event.h (create_thread_event_breakpoint): Add optional
	"thread" parameter.

doc/ChangeLog
2017-09-11  Tom Tromey  <tom@tromey.com>

	* python.texi (Events In Python): Document new events.

testsuite/ChangeLog
2017-09-11  Tom Tromey  <tom@tromey.com>

	* gdb.python/py-infthread.exp: Add tests for new_thread event.
	* gdb.python/py-inferior.exp: Add tests for new inferior events.

2 files changed, 36 insertions, 0 deletions

diff --git a/gdb/testsuite/gdb.python/py-inferior.exp b/gdb/testsuite/gdb.python/py-inferior.exp
index c2ea2c2a4bc..715c693c408 100644
--- a/gdb/testsuite/gdb.python/py-inferior.exp
+++ b/gdb/testsuite/gdb.python/py-inferior.exp
@@ -214,12 +214,33 @@ with_test_prefix "is_valid" {
     gdb_test "python print (inf_list\[0\].is_valid())" "True" \
 	"check inferior validity 1"
 
+    gdb_py_test_multiple "install new inferior event handler" \
+	"python" "" \
+	"my_inferior_count = 1" "" \
+	"def new_inf_handler(evt):" "" \
+	"  global my_inferior_count" "" \
+	"  if evt.inferior is not None:" "" \
+	"    my_inferior_count = my_inferior_count + 1" "" \
+	"gdb.events.new_inferior.connect(new_inf_handler)" "" \
+	"end" ""
+    gdb_py_test_multiple "install inferior deleted event handler" \
+	"python" "" \
+	"def del_inf_handler(evt):" "" \
+	"  global my_inferior_count" "" \
+	"  if evt.inferior is not None:" "" \
+	"    my_inferior_count = my_inferior_count - 1" "" \
+	"gdb.events.inferior_deleted.connect(del_inf_handler)" "" \
+	"end" ""
+
     gdb_test "add-inferior" "Added inferior 2.*" "add empty inferior 2"
     gdb_py_test_silent_cmd "python inf_list = gdb.inferiors()" "get new list" 1
     gdb_test "python print (len(inf_list))" "2" "get inferior list length 2"
     gdb_test "python print (inf_list\[0\].is_valid())" "True" \
 	"check inferior validity 2"
 
+    gdb_test "python print (my_inferior_count)" "2" \
+	"test new-inferior event handler"
+
     gdb_test "python print (inf_list\[1\].is_valid())" "True" \
 	"check inferior validity 3"
 
@@ -229,6 +250,9 @@ with_test_prefix "is_valid" {
 
     gdb_test "python print (inf_list\[1\].is_valid())" "False" \
 	"check inferior validity 5"
+
+    gdb_test "python print (my_inferior_count)" "1" \
+	"test inferior-deleted event handler"
 }
 
 # Test gdb.selected_inferior()
diff --git a/gdb/testsuite/gdb.python/py-infthread.exp b/gdb/testsuite/gdb.python/py-infthread.exp
index a5fed8d8934..0711d6994e8 100644
--- a/gdb/testsuite/gdb.python/py-infthread.exp
+++ b/gdb/testsuite/gdb.python/py-infthread.exp
@@ -30,6 +30,16 @@ clean_restart ${testfile}
 # Skip all tests if Python scripting is not enabled.
 if { [skip_python_tests] } { continue }
 
+gdb_py_test_multiple "install new_thread event handler" \
+    "python" "" \
+    "seen_a_thread = False" "" \
+    "def thread_handler(evt):" "" \
+    "  if evt.inferior_thread is not None:" "" \
+    "    global seen_a_thread" "" \
+    "    seen_a_thread = True" "" \
+    "gdb.events.new_thread.connect(thread_handler)" "" \
+    "end" ""
+
 # The following tests require execution.
 
 if ![runto_main] then {
@@ -37,6 +47,8 @@ if ![runto_main] then {
     return 0
 }
 
+gdb_test "python print(seen_a_thread)" "True"
+
 # Test basic gdb.Inferior attributes and methods.
 
 gdb_py_test_silent_cmd "python t0 = gdb.selected_thread ()" "test gdb.selected_thread" 1