cli: introduce a progress class

Provide a class that will display progress information to the console.
Initially, it contains callbacks for fetch progress and checkout
progress.

src/cli/progress.c

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdint.h>
+
+#include "progress.h"
+#include "error.h"
+
+#define PROGRESS_UPDATE_TIME 0.05
+
+#define is_nl(c) ((c) == '\r' || (c) == '\n')
+
+#define return_os_error(msg) do { \
+	git_error_set(GIT_ERROR_OS, "%s", msg); return -1; } while(0)
+
+GIT_INLINE(size_t) no_nl_len(const char *str, size_t len)
+{
+	size_t i = 0;
+
+	while (i < len && !is_nl(str[i]))
+		i++;
+
+	return i;
+}
+
+GIT_INLINE(size_t) nl_len(bool *has_nl, const char *str, size_t len)
+{
+	size_t i = no_nl_len(str, len);
+
+	*has_nl = false;
+
+	while (i < len && is_nl(str[i])) {
+		*has_nl = true;
+		i++;
+	}
+
+	return i;
+}
+
+static int progress_write(cli_progress *progress, bool force, git_buf *line)
+{
+	bool has_nl;
+	size_t no_nl = no_nl_len(line->ptr, line->size);
+	size_t nl = nl_len(&has_nl, line->ptr + no_nl, line->size - no_nl);
+	double now = git__timer();
+	size_t i;
+
+	/* Avoid spamming the console with progress updates */
+	if (!force && line->ptr[line->size - 1] != '\n' && progress->last_update) {
+		if (now - progress->last_update < PROGRESS_UPDATE_TIME) {
+			git_buf_clear(&progress->deferred);
+			git_buf_put(&progress->deferred, line->ptr, line->size);
+			return git_buf_oom(&progress->deferred) ? -1 : 0;
+		}
+	}
+
+	/*
+	 * If there's something on this line already (eg, a progress line
+	 * with only a trailing `\r` that we'll print over) then we need
+	 * to really print over it in case we're writing a shorter line.
+	 */
+	if (printf("%.*s", (int)no_nl, line->ptr) < 0)
+		return_os_error("could not print status");
+
+	if (progress->onscreen.size) {
+		for (i = no_nl; i < progress->onscreen.size; i++) {
+			if (printf(" ") < 0)
+				return_os_error("could not print status");
+		}
+	}
+
+	if (printf("%.*s", (int)nl, line->ptr + no_nl) < 0 ||
+	    fflush(stdout) != 0)
+		return_os_error("could not print status");
+
+	git_buf_clear(&progress->onscreen);
+
+	if (line->ptr[line->size - 1] == '\n') {
+		progress->last_update = 0;
+	} else {
+		git_buf_put(&progress->onscreen, line->ptr, line->size);
+		progress->last_update = now;
+	}
+
+	git_buf_clear(&progress->deferred);
+	return git_buf_oom(&progress->onscreen) ? -1 : 0;
+}
+
+static int progress_printf(cli_progress *progress, bool force, const char *fmt, ...)
+	GIT_FORMAT_PRINTF(3, 4);
+
+int progress_printf(cli_progress *progress, bool force, const char *fmt, ...)
+{
+	git_buf buf = GIT_BUF_INIT;
+	va_list ap;
+	int error;
+
+	va_start(ap, fmt);
+	error = git_buf_vprintf(&buf, fmt, ap);
+	va_end(ap);
+
+	if (error < 0)
+		return error;
+
+	error = progress_write(progress, force, &buf);
+
+	git_buf_dispose(&buf);
+	return error;
+}
+
+static int progress_complete(cli_progress *progress)
+{
+	if (progress->deferred.size)
+		progress_write(progress, true, &progress->deferred);
+
+	if (progress->onscreen.size)
+		if (printf("\n") < 0)
+			return_os_error("could not print status");
+
+	git_buf_clear(&progress->deferred);
+	git_buf_clear(&progress->onscreen);
+	progress->last_update = 0;
+	progress->action_start = 0;
+	progress->action_finish = 0;
+
+	return 0;
+}
+
+GIT_INLINE(int) percent(size_t completed, size_t total)
+{
+	if (total == 0)
+		return (completed == 0) ? 100 : 0;
+
+	return (int)(((double)completed / (double)total) * 100);
+}
+
+int cli_progress_fetch_sideband(const char *str, int len, void *payload)
+{
+	cli_progress *progress = (cli_progress *)payload;
+	size_t remain;
+
+	if (len <= 0)
+		return 0;
+
+	/* Accumulate the sideband data, then print it line-at-a-time. */
+	if (git_buf_put(&progress->sideband, str, len) < 0)
+		return -1;
+
+	str = progress->sideband.ptr;
+	remain = progress->sideband.size;
+
+	while (remain) {
+		bool has_nl;
+		size_t line_len = nl_len(&has_nl, str, remain);
+
+		if (!has_nl)
+			break;
+
+		if (line_len < INT_MAX) {
+			int error = progress_printf(progress, true,
+				"remote: %.*s", (int)line_len, str);
+
+			if (error < 0)
+				return error;
+		}
+
+		str += line_len;
+		remain -= line_len;
+	}
+
+	git_buf_consume_bytes(&progress->sideband, (progress->sideband.size - remain));
+
+	return 0;
+}
+
+static int fetch_receiving(
+	cli_progress *progress,
+	const git_indexer_progress *stats)
+{
+	char *recv_units[] = { "B", "KiB", "MiB", "GiB", "TiB", NULL };
+	char *rate_units[] = { "B/s", "KiB/s", "MiB/s", "GiB/s", "TiB/s", NULL };
+
+	double now, recv_len, rate, elapsed;
+	size_t recv_unit_idx = 0, rate_unit_idx = 0;
+	bool done = (stats->received_objects == stats->total_objects);
+
+	if (!progress->action_start)
+		progress->action_start = git__timer();
+
+	if (done && progress->action_finish)
+		now = progress->action_finish;
+	else if (done)
+		progress->action_finish = now = git__timer();
+	else
+		now = git__timer();
+
+	recv_len = (double)stats->received_bytes;
+
+	elapsed = now - progress->action_start;
+	rate = elapsed ? recv_len / elapsed : 0;
+	done = (stats->received_objects == stats->total_objects);
+
+	while (recv_len > 1024 && recv_units[recv_unit_idx+1]) {
+		recv_len /= 1024;
+		recv_unit_idx++;
+	}
+
+	while (rate > 1024 && rate_units[rate_unit_idx+1]) {
+		rate /= 1024;
+		rate_unit_idx++;
+	}
+
+	return progress_printf(progress, false,
+		"Receiving objects: %3d%% (%d/%d), %.2f %s | %.2f %s%s\r",
+		percent(stats->received_objects, stats->total_objects),
+		stats->received_objects,
+		stats->total_objects,
+		recv_len, recv_units[recv_unit_idx],
+		rate, rate_units[rate_unit_idx],
+		done ? ", done." : "");
+}
+
+static int fetch_resolving(
+	cli_progress *progress,
+	const git_indexer_progress *stats)
+{
+	bool done = (stats->indexed_deltas == stats->total_deltas);
+
+	return progress_printf(progress, false,
+		"Resolving deltas: %3d%% (%d/%d)%s\r",
+		percent(stats->indexed_deltas, stats->total_deltas),
+		stats->indexed_deltas, stats->total_deltas,
+		done ? ", done." : "");
+}
+
+int cli_progress_fetch_transfer(const git_indexer_progress *stats, void *payload)
+{
+	cli_progress *progress = (cli_progress *)payload;
+	int error = 0;
+
+	switch (progress->action) {
+	case CLI_PROGRESS_NONE:
+		progress->action = CLI_PROGRESS_RECEIVING;
+		/* fall through */
+
+	case CLI_PROGRESS_RECEIVING:
+		if ((error = fetch_receiving(progress, stats)) < 0)
+			break;
+
+		/*
+		 * Upgrade from receiving to resolving; do this after the
+		 * final call to cli_progress_fetch_receiving (above) to
+		 * ensure that we've printed a final "done" string after
+		 * any sideband data.
+		 */
+		if (!stats->indexed_deltas)
+			break;
+
+		progress_complete(progress);
+		progress->action = CLI_PROGRESS_RESOLVING;
+		/* fall through */
+
+	case CLI_PROGRESS_RESOLVING:
+		error = fetch_resolving(progress, stats);
+		break;
+
+	default:
+		/* should not be reached */
+		cli_die("unexpected progress state");
+	}
+
+	return error;
+}
+
+void cli_progress_checkout(
+	const char *path,
+	size_t completed_steps,
+	size_t total_steps,
+	void *payload)
+{
+	cli_progress *progress = (cli_progress *)payload;
+	bool done = (completed_steps == total_steps);
+
+	GIT_UNUSED(path);
+
+	if (progress->action != CLI_PROGRESS_CHECKING_OUT) {
+		progress_complete(progress);
+		progress->action = CLI_PROGRESS_CHECKING_OUT;
+	}
+
+	progress_printf(progress, false,
+		"Checking out files: %3d%% (%lu/%lu)%s\r",
+		percent(completed_steps, total_steps),
+		completed_steps, total_steps,
+		done ? ", done." : "");
+}
+
+int cli_progress_abort(cli_progress *progress)
+{
+	if (progress->onscreen.size > 0 && printf("\n") < 0)
+	    return_os_error("could not print status");
+
+	return 0;
+}
+
+int cli_progress_finish(cli_progress *progress)
+{
+	int error = progress->action ? progress_complete(progress) : 0;
+
+	progress->action = 0;
+	return error;
+}
+
+void cli_progress_dispose(cli_progress *progress)
+{
+	if (progress == NULL)
+		return;
+
+	git_buf_dispose(&progress->sideband);
+	git_buf_dispose(&progress->onscreen);
+	git_buf_dispose(&progress->deferred);
+
+	memset(progress, 0, sizeof(cli_progress));
+}

src/cli/progress.h

+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#ifndef CLI_progress_h__
+#define CLI_progress_h__
+
+#include <git2.h>
+#include "buffer.h"
+
+/*
+ * A general purpose set of progress printing functions.  An individual
+ * `cli_progress` object is capable of displaying progress for a single
+ * function, even if that function displays multiple pieces of progress
+ * (like `git_clone`).  `cli_progress_finish` should be called after
+ * any function invocation to re-set state.
+ */
+
+typedef enum {
+	CLI_PROGRESS_NONE,
+	CLI_PROGRESS_RECEIVING,
+	CLI_PROGRESS_RESOLVING,
+	CLI_PROGRESS_CHECKING_OUT
+} cli_progress_t;
+
+typedef struct {
+	cli_progress_t action;
+
+	/* Actions may time themselves (eg fetch) but are not required to */
+	double action_start;
+	double action_finish;
+
+	/* Last console update, avoid too frequent updates. */
+	double last_update;
+
+	/* Accumulators for partial output and deferred updates. */
+	git_buf sideband;
+	git_buf onscreen;
+	git_buf deferred;
+} cli_progress;
+
+#define CLI_PROGRESS_INIT { 0 }
+
+/**
+ * Prints sideband data from fetch to the console.  Suitable for a
+ * `sideband_progress` callback for `git_fetch_options`.
+ *
+ * @param str The sideband string
+ * @param len The length of the sideband string
+ * @param payload A pointer to the cli_progress
+ * @return 0 on success, -1 on failure
+ */
+extern int cli_progress_fetch_sideband(
+	const char *str,
+	int len,
+	void *payload);
+
+/**
+ * Prints fetch transfer statistics to the console.  Suitable for a
+ * `transfer_progress` callback for `git_fetch_options`.
+ *
+ * @param stats The indexer stats
+ * @param payload A pointer to the cli_progress
+ * @return 0 on success, -1 on failure
+ */
+extern int cli_progress_fetch_transfer(
+	const git_indexer_progress *stats,
+	void *payload);
+
+/**
+ * Prints checkout progress to the console.  Suitable for a
+ * `progress_cb` callback for `git_checkout_options`.
+ *
+ * @param path The path being written
+ * @param completed_steps The completed checkout steps
+ * @param total_steps The total number of checkout steps
+ * @param payload A pointer to the cli_progress
+ */
+extern void cli_progress_checkout(
+	const char *path,
+	size_t completed_steps,
+	size_t total_steps,
+	void *payload);
+
+/**
+ * Stop displaying progress quickly; suitable for stopping an application
+ * quickly.  Does not display any lines that were buffered, just gets the
+ * console back to a sensible place.
+ *
+ * @param progress The progress information
+ * @return 0 on success, -1 on failure
+ */
+extern int cli_progress_abort(cli_progress *progress);
+
+/**
+ * Finishes displaying progress; flushes any buffered output.
+ *
+ * @param progress The progress information
+ * @return 0 on success, -1 on failure
+ */
+extern int cli_progress_finish(cli_progress *progress);
+
+/**
+ * Disposes the progress information.
+ *
+ * @param progress The progress information
+ */
+extern void cli_progress_dispose(cli_progress *progress);
+
+#endif /* CLI_progress_h__ */