[lttng-dev] [PATCH babeltrace 2/2] CTF writer: Add function to add an integer environment field value

[Simon Marchi]

>From the Python API, it's only possible to set an environment field
value as a string (whatever you pass, it gets stringified).  This patch
adds a function to the CTF writer to allow setting an integer (int64_t)
environment field, an then exposes it in the Python interface.

The Python method Writer.add_environment_field now uses the type of the
passed value to determine which underlying C function to call (string or
integer).  Any other type is rejected.  This causes a behavior change,
since passing an integer value to add_environment_field used to produce
a string version of the value, whereas it will now produce an integer
version.  However, I think it will now behave more closely to the
expectation of a lambda user.

Example:

  w.add_environment_field("foo", 2)

Result before:

  env {
    foo = "2";
  };

Result after:

  env {
    foo = 2;
  };

Signed-off-by: Simon Marchi <simon.marchi at polymtl.ca>
---
 bindings/python/babeltrace/nativebt.i  |  2 ++
 bindings/python/babeltrace/writer.py   | 18 +++++++++++++++---
 formats/ctf/writer/writer.c            | 16 ++++++++++++++++
 include/babeltrace/ctf-writer/writer.h | 17 +++++++++++++++++
 4 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/bindings/python/babeltrace/nativebt.i b/bindings/python/babeltrace/nativebt.i
index ad20c13..345173f 100644
--- a/bindings/python/babeltrace/nativebt.i
+++ b/bindings/python/babeltrace/nativebt.i
@@ -635,6 +635,7 @@ void bt_ctf_stream_put(struct bt_ctf_stream *stream);
 %rename("_bt_ctf_writer_create") bt_ctf_writer_create(const char *path);
 %rename("_bt_ctf_writer_create_stream") bt_ctf_writer_create_stream(struct bt_ctf_writer *writer, struct bt_ctf_stream_class *stream_class);
 %rename("_bt_ctf_writer_add_environment_field") bt_ctf_writer_add_environment_field(struct bt_ctf_writer *writer, const char *name, const char *value);
+%rename("_bt_ctf_writer_add_environment_field_int64") bt_ctf_writer_add_environment_field_int64(struct bt_ctf_writer *writer, const char *name, int64_t value);
 %rename("_bt_ctf_writer_add_clock") bt_ctf_writer_add_clock(struct bt_ctf_writer *writer, struct bt_ctf_clock *clock);
 %newobject bt_ctf_writer_get_metadata_string;
 %rename("_bt_ctf_writer_get_metadata_string") bt_ctf_writer_get_metadata_string(struct bt_ctf_writer *writer);
@@ -646,6 +647,7 @@ void bt_ctf_stream_put(struct bt_ctf_stream *stream);
 struct bt_ctf_writer *bt_ctf_writer_create(const char *path);
 struct bt_ctf_stream *bt_ctf_writer_create_stream(struct bt_ctf_writer *writer, struct bt_ctf_stream_class *stream_class);
 int bt_ctf_writer_add_environment_field(struct bt_ctf_writer *writer, const char *name, const char *value);
+int bt_ctf_writer_add_environment_field_int64(struct bt_ctf_writer *writer, const char *name, int64_t value);
 int bt_ctf_writer_add_clock(struct bt_ctf_writer *writer, struct bt_ctf_clock *clock);
 char *bt_ctf_writer_get_metadata_string(struct bt_ctf_writer *writer);
 void bt_ctf_writer_flush_metadata(struct bt_ctf_writer *writer);
diff --git a/bindings/python/babeltrace/writer.py b/bindings/python/babeltrace/writer.py
index cd609af..8ed18c6 100644
--- a/bindings/python/babeltrace/writer.py
+++ b/bindings/python/babeltrace/writer.py
@@ -2141,11 +2141,23 @@ class Writer:
         Sets the CTF environment variable named *name* to value *value*
         (converted to a string).
 
-        :exc:`ValueError` is raised on error.
+        :exc:`ValueError` or `TypeError` is raised on error.
         """
 
-        ret = nbt._bt_ctf_writer_add_environment_field(self._w, str(name),
-                                                       str(value))
+        if type(name) != str:
+            raise TypeError("Field name must be a string.")
+
+        t = type(value)
+
+        if t == str:
+            ret = nbt._bt_ctf_writer_add_environment_field(self._w, name,
+                                                           value)
+        elif t == int:
+            ret = nbt._bt_ctf_writer_add_environment_field_int64(self._w,
+                                                                 name,
+                                                                 value)
+        else:
+            raise TypeError("Value type is not supported.")
 
         if ret < 0:
             raise ValueError("Could not add environment field to trace.")
diff --git a/formats/ctf/writer/writer.c b/formats/ctf/writer/writer.c
index 6c29493..012b3ef 100644
--- a/formats/ctf/writer/writer.c
+++ b/formats/ctf/writer/writer.c
@@ -209,6 +209,22 @@ end:
 	return ret;
 }
 
+int bt_ctf_writer_add_environment_field_int64(struct bt_ctf_writer *writer,
+		const char *name,
+		int64_t value)
+{
+	int ret = -1;
+
+	if (!writer || !name) {
+		goto end;
+	}
+
+	ret = bt_ctf_trace_set_environment_field_integer(writer->trace, name,
+		value);
+end:
+	return ret;
+}
+
 int bt_ctf_writer_add_clock(struct bt_ctf_writer *writer,
 		struct bt_ctf_clock *clock)
 {
diff --git a/include/babeltrace/ctf-writer/writer.h b/include/babeltrace/ctf-writer/writer.h
index 940736f..140bc5f 100644
--- a/include/babeltrace/ctf-writer/writer.h
+++ b/include/babeltrace/ctf-writer/writer.h
@@ -96,6 +96,23 @@ extern int bt_ctf_writer_add_environment_field(struct bt_ctf_writer *writer,
 		const char *value);
 
 /*
+ * bt_ctf_writer_add_environment_field_int64: add an environment field to the trace.
+ *
+ * Add an environment field to the trace. The name and value parameters are
+ * copied.
+ *
+ * @param writer Writer instance.
+ * @param name Name of the environment field (will be copied).
+ * @param value Value of the environment field.
+ *
+ * Returns 0 on success, a negative value on error.
+ */
+extern int bt_ctf_writer_add_environment_field_int64(
+		struct bt_ctf_writer *writer,
+		const char *name,
+		int64_t value);
+
+/*
  * bt_ctf_writer_add_clock: add a clock to the trace.
  *
  * Add a clock to the trace. Clocks assigned to stream classes must be
-- 
2.8.3