Re: [PATCH BlueZ] mesh: Move sequence number overcommit to mesh-config-json

["Gix, Brian" <brian.gix@intel.com>]

Applied with cosmetic block-comment "style guide" adjustment

On Wed, 2019-08-07 at 11:58 +0200, Michał Lowas-Rzechonek wrote:
> This confines sequence overcommit logic in mesh-config-json, as other
> storages might use a different mechanism to ensure reliability.
> 
> Also, refactored logic to calculate overcommit value to avoid division
> by zero when messages are sent too fast.
> ---
>  mesh/mesh-config-json.c | 70 +++++++++++++++++++++++++++++++++++++++--
>  mesh/mesh-config.h      |  3 +-
>  mesh/net.c              | 18 +++--------
>  mesh/node.c             | 56 +++------------------------------
>  mesh/node.h             |  6 ----
>  5 files changed, 78 insertions(+), 75 deletions(-)
> 
> diff --git a/mesh/mesh-config-json.c b/mesh/mesh-config-json.c
> index d49f5226a..e3a804d35 100644
> --- a/mesh/mesh-config-json.c
> +++ b/mesh/mesh-config-json.c
> @@ -31,6 +31,8 @@
>  #include <string.h>
>  #include <unistd.h>
>  
> +#include <sys/time.h>
> +
>  #include <ell/ell.h>
>  #include <json-c/json.h>
>  
> @@ -38,12 +40,19 @@
>  #include "mesh/util.h"
>  #include "mesh/mesh-config.h"
>  
> +/* To prevent local node JSON cache thrashing, minimum update times */
> +#define MIN_SEQ_CACHE_TRIGGER	32
> +#define MIN_SEQ_CACHE_VALUE	(2 * 32)
> +#define MIN_SEQ_CACHE_TIME	(5 * 60)
> +
>  #define CHECK_KEY_IDX_RANGE(x) (((x) >= 0) && ((x) <= 4095))
>  
>  struct mesh_config {
>  	json_object *jnode;
>  	char *node_dir_path;
>  	uint8_t uuid[16];
> +	uint32_t write_seq;
> +	struct timeval write_time;
>  };
>  
>  struct write_info {
> @@ -1708,6 +1717,8 @@ static struct mesh_config *create_config(const char *cfg_path,
>  	cfg->jnode = jnode;
>  	memcpy(cfg->uuid, uuid, 16);
>  	cfg->node_dir_path = l_strdup(cfg_path);
> +	cfg->write_seq = node->seq_number;
> +	gettimeofday(&cfg->write_time, NULL);
>  
>  	return cfg;
>  }
> @@ -2020,12 +2031,59 @@ bool mesh_config_model_sub_del_all(struct mesh_config *cfg, uint16_t addr,
>  	return save_config(cfg->jnode, cfg->node_dir_path);
>  }
>  
> -bool mesh_config_write_seq_number(struct mesh_config *cfg, uint32_t seq)
> +bool mesh_config_write_seq_number(struct mesh_config *cfg, uint32_t seq,
> +								bool cache)
>  {
> -	if (!cfg || !write_int(cfg->jnode, "sequenceNumber", seq))
> +	int value;
> +	uint32_t cached = 0;
> +
> +	if (!cfg)
>  		return false;
>  
> -	mesh_config_save(cfg, false, NULL, NULL);
> +	if (!cache) {
> +		if (!write_int(cfg->jnode, "sequenceNumber", seq))
> +		    return false;
> +
> +		return mesh_config_save(cfg, true, NULL, NULL);
> +	}
> +
> +	if (get_int(cfg->jnode, "sequenceNumber", &value))
> +		cached = (uint32_t)value;
> +
> +	/*
> +	 * When sequence number approaches value stored on disk, calculate
> +	 * average time between sequence number updates, then overcommit the
> +	 * sequence number by MIN_SEQ_CACHE_TIME seconds worth of traffic or
> +	 * MIN_SEQ_CACHE_VALUE (whichever is greater) to avoid frequent writes
> +	 * to disk and to protect against crashes.
> +	 *
> +	 * The real value will be saved when daemon shuts down properly.
> +	*/
> +	if (seq + MIN_SEQ_CACHE_TRIGGER >= cached) {
> +		struct timeval now;
> +		struct timeval elapsed;
> +		uint64_t elapsed_ms;
> +
> +		gettimeofday(&now, NULL);
> +		timersub(&now, &cfg->write_time, &elapsed);
> +		elapsed_ms = elapsed.tv_sec * 1000 + elapsed.tv_usec / 1000;
> +
> +		cached = seq + (seq - cfg->write_seq) *
> +					1000 * MIN_SEQ_CACHE_TIME / elapsed_ms;
> +
> +		if (cached < seq + MIN_SEQ_CACHE_VALUE)
> +			cached = seq + MIN_SEQ_CACHE_VALUE;
> +
> +		l_debug("Seq Cache: %d -> %d", seq, cached);
> +
> +		cfg->write_seq = seq;
> +
> +		if (!write_int(cfg->jnode, "sequenceNumber", cached))
> +		    return false;
> +
> +		return mesh_config_save(cfg, false, NULL, NULL);
> +	}
> +
>  	return true;
>  }
>  
> @@ -2089,6 +2147,9 @@ static bool load_node(const char *fname, const uint8_t uuid[16],
>  		cfg->jnode = jnode;
>  		memcpy(cfg->uuid, uuid, 16);
>  		cfg->node_dir_path = l_strdup(fname);
> +		cfg->write_seq = node.seq_number;
> +		gettimeofday(&cfg->write_time, NULL);
> +
>  		result = cb(&node, uuid, cfg, user_data);
>  
>  		if (!result) {
> @@ -2147,10 +2208,13 @@ static void idle_save_config(void *user_data)
>  	l_free(fname_tmp);
>  	l_free(fname_bak);
>  
> +	gettimeofday(&info->cfg->write_time, NULL);
> +
>  	if (info->cb)
>  		info->cb(info->user_data, result);
>  
>  	l_free(info);
> +
>  }
>  
>  bool mesh_config_save(struct mesh_config *cfg, bool no_wait,
> diff --git a/mesh/mesh-config.h b/mesh/mesh-config.h
> index 44e3b3ad6..4172e794b 100644
> --- a/mesh/mesh-config.h
> +++ b/mesh/mesh-config.h
> @@ -128,7 +128,8 @@ bool mesh_config_write_network_key(struct mesh_config *cfg, uint16_t idx,
>  				uint8_t *key, uint8_t *new_key, int phase);
>  bool mesh_config_write_app_key(struct mesh_config *cfg, uint16_t net_idx,
>  			uint16_t app_idx, uint8_t *key, uint8_t *new_key);
> -bool mesh_config_write_seq_number(struct mesh_config *cfg, uint32_t seq);
> +bool mesh_config_write_seq_number(struct mesh_config *cfg, uint32_t seq,
> +								bool cache);
>  bool mesh_config_write_unicast(struct mesh_config *cfg, uint16_t unicast);
>  bool mesh_config_write_relay_mode(struct mesh_config *cfg, uint8_t mode,
>  					uint8_t count, uint16_t interval);
> diff --git a/mesh/net.c b/mesh/net.c
> index 7c92cfd5e..7c4049e0e 100644
> --- a/mesh/net.c
> +++ b/mesh/net.c
> @@ -133,7 +133,6 @@ struct mesh_net {
>  	uint32_t instant; /* Controller Instant of recent Rx */
>  	uint32_t iv_index;
>  	uint32_t seq_num;
> -	uint32_t cached_seq_num;
>  	uint16_t src_addr;
>  	uint16_t last_addr;
>  	uint16_t friend_addr;
> @@ -503,17 +502,8 @@ void mesh_friend_sub_del(struct mesh_net *net, uint16_t lpn,
>  
>  uint32_t mesh_net_next_seq_num(struct mesh_net *net)
>  {
> -	uint32_t seq = net->seq_num;
> -
> -	net->seq_num++;
> -
> -	/* Periodically store advanced sequence number */
> -	if (net->seq_num + MIN_SEQ_TRIGGER >= net->cached_seq_num) {
> -		net->cached_seq_num = net->seq_num +
> -					node_seq_cache(net->node);
> -		node_set_sequence_number(net->node, net->cached_seq_num);
> -	}
> -
> +	uint32_t seq = net->seq_num++;
> +	node_set_sequence_number(net->node, net->seq_num);
>  	return seq;
>  }
>  
> @@ -722,12 +712,12 @@ void mesh_net_free(struct mesh_net *net)
>  	l_free(net);
>  }
>  
> -bool mesh_net_set_seq_num(struct mesh_net *net, uint32_t number)
> +bool mesh_net_set_seq_num(struct mesh_net *net, uint32_t seq)
>  {
>  	if (!net)
>  		return false;
>  
> -	net->cached_seq_num = net->seq_num = number;
> +	net->seq_num = seq;
>  
>  	return true;
>  }
> diff --git a/mesh/node.c b/mesh/node.c
> index bff73cfc7..e7e58d9a7 100644
> --- a/mesh/node.c
> +++ b/mesh/node.c
> @@ -25,8 +25,6 @@
>  #include <dirent.h>
>  #include <stdio.h>
>  
> -#include <sys/time.h>
> -
>  #include <ell/ell.h>
>  
>  #include "mesh/mesh-defs.h"
> @@ -90,9 +88,7 @@ struct mesh_node {
>  	struct mesh_config *cfg;
>  	char *storage_dir;
>  	uint32_t disc_watch;
> -	time_t upd_sec;
>  	uint32_t seq_number;
> -	uint32_t seq_min_cache;
>  	bool provisioner;
>  	uint16_t primary;
>  	struct node_composition *comp;
> @@ -560,15 +556,11 @@ static void cleanup_node(void *data)
>  	struct mesh_node *node = data;
>  	struct mesh_net *net = node->net;
>  
> -	/* Save local node configuration */
> -	if (node->cfg) {
> -
> -		/* Preserve the last sequence number */
> +	/* Preserve the last sequence number */
> +	if (node->cfg)
>  		mesh_config_write_seq_number(node->cfg,
> -						mesh_net_get_seq_num(net));
> -
> -		mesh_config_save(node->cfg, true, NULL, NULL);
> -	}
> +						mesh_net_get_seq_num(net),
> +						false);
>  
>  	free_node_resources(node);
>  }
> @@ -704,42 +696,12 @@ bool node_default_ttl_set(struct mesh_node *node, uint8_t ttl)
>  
>  bool node_set_sequence_number(struct mesh_node *node, uint32_t seq)
>  {
> -	struct timeval write_time;
> -
>  	if (!node)
>  		return false;
>  
>  	node->seq_number = seq;
>  
> -	/*
> -	 * Holistically determine worst case 5 minute sequence consumption
> -	 * so that we typically (once we reach a steady state) rewrite the
> -	 * local node file with a new seq cache value no more than once every
> -	 * five minutes (or more)
> -	 */
> -	gettimeofday(&write_time, NULL);
> -	if (node->upd_sec) {
> -		uint32_t elapsed = write_time.tv_sec - node->upd_sec;
> -
> -		if (elapsed < MIN_SEQ_CACHE_TIME) {
> -			uint32_t ideal = node->seq_min_cache;
> -
> -			l_debug("Old Seq Cache: %d", node->seq_min_cache);
> -
> -			ideal *= (MIN_SEQ_CACHE_TIME / elapsed);
> -
> -			if (ideal > node->seq_min_cache + MIN_SEQ_CACHE)
> -				node->seq_min_cache = ideal;
> -			else
> -				node->seq_min_cache += MIN_SEQ_CACHE;
> -
> -			l_debug("New Seq Cache: %d", node->seq_min_cache);
> -		}
> -	}
> -
> -	node->upd_sec = write_time.tv_sec;
> -
> -	return mesh_config_write_seq_number(node->cfg, seq);
> +	return mesh_config_write_seq_number(node->cfg, node->seq_number, true);
>  }
>  
>  uint32_t node_get_sequence_number(struct mesh_node *node)
> @@ -750,14 +712,6 @@ uint32_t node_get_sequence_number(struct mesh_node *node)
>  	return node->seq_number;
>  }
>  
> -uint32_t node_seq_cache(struct mesh_node *node)
> -{
> -	if (node->seq_min_cache < MIN_SEQ_CACHE)
> -		node->seq_min_cache = MIN_SEQ_CACHE;
> -
> -	return node->seq_min_cache;
> -}
> -
>  int node_get_element_idx(struct mesh_node *node, uint16_t ele_addr)
>  {
>  	uint16_t addr;
> diff --git a/mesh/node.h b/mesh/node.h
> index a4cac028d..be57d5e67 100644
> --- a/mesh/node.h
> +++ b/mesh/node.h
> @@ -24,11 +24,6 @@ struct mesh_agent;
>  struct mesh_config;
>  struct mesh_config_node;
>  
> -/* To prevent local node JSON cache thrashing, minimum update times */
> -#define MIN_SEQ_TRIGGER	32
> -#define MIN_SEQ_CACHE		(2*MIN_SEQ_TRIGGER)
> -#define MIN_SEQ_CACHE_TIME	(5*60)
> -
>  typedef void (*node_ready_func_t) (void *user_data, int status,
>  							struct mesh_node *node);
>  
> @@ -82,7 +77,6 @@ bool node_beacon_mode_set(struct mesh_node *node, bool enable);
>  uint8_t node_beacon_mode_get(struct mesh_node *node);
>  bool node_friend_mode_set(struct mesh_node *node, bool enable);
>  uint8_t node_friend_mode_get(struct mesh_node *node);
> -uint32_t node_seq_cache(struct mesh_node *node);
>  const char *node_get_element_path(struct mesh_node *node, uint8_t ele_idx);
>  const char *node_get_owner(struct mesh_node *node);
>  const char *node_get_app_path(struct mesh_node *node);