util: make monotonic time fn return ms

`git__timer` is now `git_time_monotonic`, and returns milliseconds
since an arbitrary epoch.

Using a floating point to store the number of seconds elapsed was
clever, as it better supports the wide range of precision from the
different monotonic clocks of different systems. But we're a version
control system, not a real-time clock.

Milliseconds is a good enough precision for our work _and_ it's the
units that system calls like `poll` take and that our users interact
with.

Make `git_time_monotonic` return the monotonically increasing number
of milliseconds "ticked" since some arbitrary epoch.

3 files changed, 13 insertions, 11 deletions

diff --git a/src/libgit2/pack-objects.c b/src/libgit2/pack-objects.c
index d6fd60326..fc8efc65f 100644
--- a/src/libgit2/pack-objects.c
+++ b/src/libgit2/pack-objects.c
@@ -255,10 +255,10 @@ int git_packbuilder_insert(git_packbuilder *pb, const git_oid *oid,
 	pb->done = false;
 
 	if (pb->progress_cb) {
-		double current_time = git__timer();
-		double elapsed = current_time - pb->last_progress_report_time;
+		uint64_t current_time = git_time_monotonic();
+		uint64_t elapsed = current_time - pb->last_progress_report_time;
 
-		if (elapsed < 0 || elapsed >= MIN_PROGRESS_UPDATE_INTERVAL) {
+		if (elapsed >= MIN_PROGRESS_UPDATE_INTERVAL) {
 			pb->last_progress_report_time = current_time;
 
 			ret = pb->progress_cb(
@@ -934,10 +934,10 @@ static int report_delta_progress(
 	int ret;
 
 	if (pb->progress_cb) {
-		double current_time = git__timer();
-		double elapsed = current_time - pb->last_progress_report_time;
+		uint64_t current_time = git_time_monotonic();
+		uint64_t elapsed = current_time - pb->last_progress_report_time;
 
-		if (force || elapsed < 0 || elapsed >= MIN_PROGRESS_UPDATE_INTERVAL) {
+		if (force || elapsed >= MIN_PROGRESS_UPDATE_INTERVAL) {
 			pb->last_progress_report_time = current_time;
 
 			ret = pb->progress_cb(
diff --git a/src/libgit2/pack-objects.h b/src/libgit2/pack-objects.h
index c6bc52fdc..0ceebc23c 100644
--- a/src/libgit2/pack-objects.h
+++ b/src/libgit2/pack-objects.h
@@ -96,7 +96,9 @@ struct git_packbuilder {
 
 	git_packbuilder_progress progress_cb;
 	void *progress_cb_payload;
-	double last_progress_report_time; /* the time progress was last reported */
+
+	/* the time progress was last reported, in millisecond ticks */
+	uint64_t last_progress_report_time;
 
 	bool done;
 };
diff --git a/src/libgit2/transports/smart_protocol.c b/src/libgit2/transports/smart_protocol.c
index 488ef07c0..f7a567829 100644
--- a/src/libgit2/transports/smart_protocol.c
+++ b/src/libgit2/transports/smart_protocol.c
@@ -1114,7 +1114,7 @@ struct push_packbuilder_payload
 	git_push_transfer_progress_cb cb;
 	void *cb_payload;
 	size_t last_bytes;
-	double last_progress_report_time;
+	uint64_t last_progress_report_time;
 };
 
 static int stream_thunk(void *buf, size_t size, void *data)
@@ -1126,11 +1126,11 @@ static int stream_thunk(void *buf, size_t size, void *data)
 		return error;
 
 	if (payload->cb) {
-		double current_time = git__timer();
-		double elapsed = current_time - payload->last_progress_report_time;
+		uint64_t current_time = git_time_monotonic();
+		uint64_t elapsed = current_time - payload->last_progress_report_time;
 		payload->last_bytes += size;
 
-		if (elapsed < 0 || elapsed >= MIN_PROGRESS_UPDATE_INTERVAL) {
+		if (elapsed >= MIN_PROGRESS_UPDATE_INTERVAL) {
 			payload->last_progress_report_time = current_time;
 			error = payload->cb(payload->pb->nr_written, payload->pb->nr_objects, payload->last_bytes, payload->cb_payload);
 		}