MINOR: stats: apply stats-file on process startup

This commit is the first one of a serie to implement preloading of
haproxy counters via stats-file parsing.

This patch defines a basic apply_stats_file() function. It implements
reading line by line of a stats-file without any parsing for the moment.
It is called automatically on process startup via init().

include/haproxy/global-t.h

@@ -155,6 +155,7 @@ struct global {
 	char *log_send_hostname;   /* set hostname in syslog header */
 	char *server_state_base;   /* path to a directory where server state files can be found */
 	char *server_state_file;   /* path to the file where server states are loaded from */
+	char *stats_file;          /* path to stats-file */
 	unsigned char cluster_secret[16]; /* 128 bits of an SHA1 digest of a secret defined as ASCII string */
 	struct {
 		int maxpollevents; /* max number of poll events at once */

include/haproxy/stats-file.h

@@ -12,4 +12,12 @@ int stats_dump_fields_file(struct buffer *out,
 
 void stats_dump_file_header(int type, struct buffer *out);
 
+/* Maximun number of parsed stat column in a header line.
+ * Directly based on ST_I_PX_MAX, with value doubled to obtain compatibility
+ * between haproxy adjacent versions.
+ */
+#define STAT_FILE_MAX_COL_COUNT    (ST_I_PX_MAX*2)
+
+void apply_stats_file(void);
+
 #endif /* _HAPROXY_STATS_FILE_H */

include/haproxy/stats-t.h

@@ -22,6 +22,7 @@
 #ifndef _HAPROXY_STATS_T_H
 #define _HAPROXY_STATS_T_H
 
+#include <import/ebtree-t.h>
 #include <haproxy/api-t.h>
 #include <haproxy/buf-t.h>
 
@@ -479,6 +480,12 @@ enum stat_idx_px {
 	ST_I_PX_MAX
 };
 
+/* Node for name-indexed stat tree from generate_stat_tree(). */
+struct stcol_node {
+	const struct stat_col *col;
+	struct ebmb_node name;
+};
+
 struct field {
 	uint32_t type;
 	union {

include/haproxy/stats.h

@@ -47,6 +47,8 @@ extern THREAD_LOCAL struct field stat_line_info[];
 extern THREAD_LOCAL struct field *stat_lines[];
 extern struct name_desc *stat_cols[STATS_DOMAIN_COUNT];
 
+int generate_stat_tree(struct eb_root *st_tree, const struct stat_col cols[]);
+
 struct htx;
 int stats_putchk(struct appctx *appctx, struct buffer *buf, struct htx *htx);
 

src/haproxy.c

@@ -118,6 +118,7 @@
 #include <haproxy/sock.h>
 #include <haproxy/sock_inet.h>
 #include <haproxy/ssl_sock.h>
+#include <haproxy/stats-file.h>
 #include <haproxy/stats-t.h>
 #include <haproxy/stream.h>
 #include <haproxy/task.h>
@@ -2365,6 +2366,9 @@ static void init(int argc, char **argv)
 	/* Apply server states */
 	apply_server_state();
 
+	/* Preload internal counters. */
+	apply_stats_file();
+
 	for (px = proxies_list; px; px = px->next)
 		srv_compute_all_admin_states(px);
 
@@ -2943,6 +2947,7 @@ void deinit(void)
 	ha_free(&localpeer);
 	ha_free(&global.server_state_base);
 	ha_free(&global.server_state_file);
+	ha_free(&global.stats_file);
 	task_destroy(idle_conn_task);
 	idle_conn_task = NULL;
 

src/stats-file.c

@@ -1,8 +1,15 @@
 #include <haproxy/stats-file.h>
 
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <import/ebmbtree.h>
 #include <haproxy/api.h>
 #include <haproxy/buf.h>
 #include <haproxy/chunk.h>
+#include <haproxy/errors.h>
+#include <haproxy/global.h>
 #include <haproxy/guid-t.h>
 #include <haproxy/list.h>
 #include <haproxy/listener-t.h>
@@ -90,3 +97,52 @@ void stats_dump_file_header(int type, struct buffer *out)
 
 	chunk_strcat(out, "\n");
 }
+
+/* Parse a stats-file and preload haproxy internal counters. */
+void apply_stats_file(void)
+{
+	struct eb_root st_tree = EB_ROOT;
+	FILE *file;
+	char *line = NULL;
+	ssize_t len;
+	size_t alloc_len;
+	int linenum;
+
+	if (!global.stats_file)
+		return;
+
+	file = fopen(global.stats_file, "r");
+	if (!file) {
+		ha_warning("config: Can't load stats file: cannot open file.\n");
+		return;
+	}
+
+	/* Generate stat columns map indexed by name. */
+	if (generate_stat_tree(&st_tree, stat_cols_px)) {
+		ha_warning("config: Can't load stats file: not enough memory.\n");
+		goto out;
+	}
+
+	linenum = 0;
+	while (1) {
+		len = getline(&line, &alloc_len, file);
+		if (len < 0)
+			break;
+
+		++linenum;
+		if (!len || (len == 1 && line[0] == '\n'))
+			continue;
+	}
+
+ out:
+	while (!eb_is_empty(&st_tree)) {
+		struct ebmb_node *node = ebmb_first(&st_tree);
+		struct stcol_node *snode = ebmb_entry(node, struct stcol_node, name);
+
+		ebmb_delete(node);
+		ha_free(&snode);
+	}
+
+	ha_free(&line);
+	fclose(file);
+}

src/stats.c

@@ -23,6 +23,7 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 
+#include <import/ebsttree.h>
 #include <haproxy/api.h>
 #include <haproxy/activity.h>
 #include <haproxy/applet.h>
@@ -336,6 +337,36 @@ struct list stats_module_list[STATS_DOMAIN_COUNT] = {
 
 THREAD_LOCAL void *trash_counters;
 
+/* Insert into <st_tree> all stat columns from <cols> indexed by their name. */
+int generate_stat_tree(struct eb_root *st_tree, const struct stat_col cols[])
+{
+	const struct stat_col *col;
+	struct stcol_node *node;
+	size_t len;
+	int i;
+
+	for (i = 0; i < ST_I_PX_MAX; ++i) {
+		col = &cols[i];
+		if (stcol_nature(col) == FN_COUNTER) {
+			len = strlen(col->name);
+			node = malloc(sizeof(struct stcol_node) + len + 1);
+			if (!node)
+				goto err;
+
+			node->col = col;
+			memcpy(node->name.key, col->name, len);
+			node->name.key[len] = '\0';
+
+			ebst_insert(st_tree, &node->name);
+		}
+	}
+
+	return 0;
+
+ err:
+	return 1;
+}
+
 
 int stats_putchk(struct appctx *appctx, struct buffer *buf, struct htx *htx)
 {