[PATCH 1/2] trace: add trace_print_string_list_key

[Stefan Beller <sbeller@google.com>]

Similar to trace_strbuf or trace_argv_printf, we might want to output
a string list in tracing. Add such a function.

Signed-off-by: Stefan Beller <sbeller@google.com>
---

I separated this from the other series, making it into 2 patches:
This first patch adds tracing for string lists and the next patch that
removes the unused function from the string list API.
That way we can decide on these two patches separately if needed.

 Documentation/technical/api-trace.txt |  8 ++++++
 trace.c                               | 39 +++++++++++++++++++++++++++
 trace.h                               | 16 +++++++++++
 3 files changed, 63 insertions(+)

diff --git a/Documentation/technical/api-trace.txt b/Documentation/technical/api-trace.txt
index fadb5979c48..ad0ea99d930 100644
--- a/Documentation/technical/api-trace.txt
+++ b/Documentation/technical/api-trace.txt
@@ -62,6 +62,14 @@ Functions
 	Prints the strbuf, without additional formatting (i.e. doesn't
 	choke on `%` or even `\0`).
 
+`void trace_print_string_list_key(struct trace_key *key, const struct string_list *p, const char *text)::
+
+	Print the string-pointer pairs of the string_list,
+	each one in its own line.
+	It takes an optional key and header argument.
+	If the tracing key is not given, use the default key.
+	The header text is printed before the list itself.
+
 `uint64_t getnanotime(void)`::
 
 	Returns nanoseconds since the epoch (01/01/1970), typically used
diff --git a/trace.c b/trace.c
index fc623e91fdd..e3a12a092f9 100644
--- a/trace.c
+++ b/trace.c
@@ -176,6 +176,38 @@ void trace_strbuf_fl(const char *file, int line, struct trace_key *key,
 	strbuf_release(&buf);
 }
 
+void trace_print_string_list_key_fl(const char *file, int line,
+				    struct trace_key *key,
+				    const struct string_list *p,
+				    const char *text)
+{
+	int i, buf_prefix;
+	struct strbuf buf = STRBUF_INIT;
+
+	if (!key)
+		key = &trace_default_key;
+
+	if (!prepare_trace_line(file, line, key, &buf))
+		return;
+
+	buf_prefix = buf.len;
+
+	if (text) {
+		strbuf_addstr(&buf, text);
+		print_trace_line(key, &buf);
+	}
+
+	for (i = 0; i < p->nr; i++) {
+		strbuf_setlen(&buf, buf_prefix);
+		strbuf_addf(&buf, "%s:%p\n",
+			    p->items[i].string,
+			    p->items[i].util);
+		print_trace_line(key, &buf);
+	}
+
+	strbuf_release(&buf);
+}
+
 static void trace_performance_vprintf_fl(const char *file, int line,
 					 uint64_t nanos, const char *format,
 					 va_list ap)
@@ -227,6 +259,13 @@ void trace_strbuf(struct trace_key *key, const struct strbuf *data)
 	trace_strbuf_fl(NULL, 0, key, data);
 }
 
+void trace_print_string_list_key(struct trace_key *key,
+				 const struct string_list *p,
+				 const char *text)
+{
+	trace_print_string_list_key_fl(NULL, 0, key, p, list);
+}
+
 void trace_performance(uint64_t nanos, const char *format, ...)
 {
 	va_list ap;
diff --git a/trace.h b/trace.h
index 2b6a1bc17c2..0e083891e1f 100644
--- a/trace.h
+++ b/trace.h
@@ -37,6 +37,10 @@ extern void trace_argv_printf(const char **argv, const char *format, ...);
 
 extern void trace_strbuf(struct trace_key *key, const struct strbuf *data);
 
+extern void trace_print_string_list_key(struct trace_key *key,
+					const struct string_list *p,
+					const char *text);
+
 /* Prints elapsed time (in nanoseconds) if GIT_TRACE_PERFORMANCE is enabled. */
 __attribute__((format (printf, 2, 3)))
 extern void trace_performance(uint64_t nanos, const char *format, ...);
@@ -103,6 +107,13 @@ extern void trace_performance_since(uint64_t start, const char *format, ...);
 			trace_strbuf_fl(TRACE_CONTEXT, __LINE__, key, data);\
 	} while (0)
 
+#define trace_print_string_list_key(key, list, text) 			    \
+	do {								    \
+		if (trace_pass_fl(key))					    \
+			trace_print_string_list_key_fl(TRACE_CONTEXT,	    \
+						       __LINE__, key, data);\
+	} while (0)
+
 #define trace_performance(nanos, ...)					    \
 	do {								    \
 		if (trace_pass_fl(&trace_perf_key))			    \
@@ -127,6 +138,11 @@ extern void trace_argv_printf_fl(const char *file, int line, const char **argv,
 				 const char *format, ...);
 extern void trace_strbuf_fl(const char *file, int line, struct trace_key *key,
 			    const struct strbuf *data);
+extern void trace_print_string_list_key_fl(const char *file, int line,
+					   struct trace_key *key,
+					   const struct string_list *p,
+					   const char *text);
+
 __attribute__((format (printf, 4, 5)))
 extern void trace_performance_fl(const char *file, int line,
 				 uint64_t nanos, const char *fmt, ...);
-- 
2.19.0.rc2.392.g5ba43deb5a-goog