Quoting Mark Wu (2013-10-08 01:23:09)
> In the original code, qmp_get_command_list is used to construct
> a list of all commands' name. To get the information of all qga
> commands, it traverses the name list and search the command info
> with its name. So it can cause O(n^2) in the number of commands.
>
> This patch adds an interface to traverse the qmp command list by
> QmpCommand to replace qmp_get_command_list. It can decrease the
> complexity from O(n^2) to O(n).
>
> Signed-off-by: Mark Wu <wu...@linux.vnet.ibm.com>
> ---
> Changes:
> v2:
> 1. Keep the signature of qmp_command_is_enabled (per Eric and Michael)
> 2. Remove the unnecessary pointer castings (per Eric)
>
> include/qapi/qmp/dispatch.h | 5 ++--
> qapi/qmp-registry.c | 27 +++---------------
> qga/commands.c | 38 ++++++++++---------------
> qga/main.c | 68
> +++++++++++++++++----------------------------
> 4 files changed, 48 insertions(+), 90 deletions(-)
>
> diff --git a/include/qapi/qmp/dispatch.h b/include/qapi/qmp/dispatch.h
> index 1ce11f5..b6eb49e 100644
> --- a/include/qapi/qmp/dispatch.h
> +++ b/include/qapi/qmp/dispatch.h
> @@ -47,9 +47,10 @@ QmpCommand *qmp_find_command(const char *name);
> QObject *qmp_dispatch(QObject *request);
> void qmp_disable_command(const char *name);
> void qmp_enable_command(const char *name);
> -bool qmp_command_is_enabled(const char *name);
> -char **qmp_get_command_list(void);
> +bool qmp_command_is_enabled(const QmpCommand *cmd);
> QObject *qmp_build_error_object(Error *errp);
> +typedef void (*qmp_cmd_callback_fn)(QmpCommand *cmd, void *opaque);
> +void qmp_for_each_command(qmp_cmd_callback_fn fn, void *opaque);
>
> #endif
>
> diff --git a/qapi/qmp-registry.c b/qapi/qmp-registry.c
> index 28bbbe8..3fcf10e 100644
> --- a/qapi/qmp-registry.c
> +++ b/qapi/qmp-registry.c
> @@ -66,35 +66,16 @@ void qmp_enable_command(const char *name)
> qmp_toggle_command(name, true);
> }
>
> -bool qmp_command_is_enabled(const char *name)
> +bool qmp_command_is_enabled(const QmpCommand *cmd)
> {
> - QmpCommand *cmd;
> -
> - QTAILQ_FOREACH(cmd, &qmp_commands, node) {
> - if (strcmp(cmd->name, name) == 0) {
> - return cmd->enabled;
> - }
> - }
> -
> - return false;
> + return cmd->enabled;
> }
>
> -char **qmp_get_command_list(void)
> +void qmp_for_each_command(qmp_cmd_callback_fn fn, void *opaque)
> {
> QmpCommand *cmd;
> - int count = 1;
> - char **list_head, **list;
> -
> - QTAILQ_FOREACH(cmd, &qmp_commands, node) {
> - count++;
> - }
> -
> - list_head = list = g_malloc0(count * sizeof(char *));
>
> QTAILQ_FOREACH(cmd, &qmp_commands, node) {
> - *list = g_strdup(cmd->name);
> - list++;
> + fn(cmd, opaque);
> }
> -
> - return list_head;
> }
> diff --git a/qga/commands.c b/qga/commands.c
> index 528b082..063b22b 100644
> --- a/qga/commands.c
> +++ b/qga/commands.c
> @@ -45,35 +45,27 @@ void qmp_guest_ping(Error **err)
> slog("guest-ping called");
> }
>
> -struct GuestAgentInfo *qmp_guest_info(Error **err)
> +static void qmp_command_info(QmpCommand *cmd, void *opaque)
> {
> - GuestAgentInfo *info = g_malloc0(sizeof(GuestAgentInfo));
> + GuestAgentInfo *info = opaque;
> GuestAgentCommandInfo *cmd_info;
> GuestAgentCommandInfoList *cmd_info_list;
> - char **cmd_list_head, **cmd_list;
> -
> - info->version = g_strdup(QEMU_VERSION);
> -
> - cmd_list_head = cmd_list = qmp_get_command_list();
> - if (*cmd_list_head == NULL) {
> - goto out;
> - }
>
> - while (*cmd_list) {
> - cmd_info = g_malloc0(sizeof(GuestAgentCommandInfo));
> - cmd_info->name = g_strdup(*cmd_list);
> - cmd_info->enabled = qmp_command_is_enabled(cmd_info->name);
> + cmd_info = g_malloc0(sizeof(GuestAgentCommandInfo));
> + cmd_info->name = g_strdup(cmd->name);
> + cmd_info->enabled = qmp_command_is_enabled(cmd);
>
> - cmd_info_list = g_malloc0(sizeof(GuestAgentCommandInfoList));
> - cmd_info_list->value = cmd_info;
> - cmd_info_list->next = info->supported_commands;
> - info->supported_commands = cmd_info_list;
> + cmd_info_list = g_malloc0(sizeof(GuestAgentCommandInfoList));
> + cmd_info_list->value = cmd_info;
> + cmd_info_list->next = info->supported_commands;
> + info->supported_commands = cmd_info_list;
> +}
>
> - g_free(*cmd_list);
> - cmd_list++;
> - }
> +struct GuestAgentInfo *qmp_guest_info(Error **err)
> +{
> + GuestAgentInfo *info = g_malloc0(sizeof(GuestAgentInfo));
>
> -out:
> - g_free(cmd_list_head);
> + info->version = g_strdup(QEMU_VERSION);
> + qmp_for_each_command(qmp_command_info, info);
> return info;
> }
> diff --git a/qga/main.c b/qga/main.c
> index 6c746c8..ff2ee03 100644
> --- a/qga/main.c
> +++ b/qga/main.c
> @@ -347,48 +347,34 @@ static gint ga_strcmp(gconstpointer str1, gconstpointer
> str2)
> }
>
> /* disable commands that aren't safe for fsfreeze */
> -static void ga_disable_non_whitelisted(void)
> +static void ga_disable_non_whitelisted(QmpCommand *cmd, void *opaque)
> {
> - char **list_head, **list;
> bool whitelisted;
> int i;
>
> - list_head = list = qmp_get_command_list();
> - while (*list != NULL) {
> - whitelisted = false;
> - i = 0;
> - while (ga_freeze_whitelist[i] != NULL) {
> - if (strcmp(*list, ga_freeze_whitelist[i]) == 0) {
> - whitelisted = true;
> - }
> - i++;
> - }
> - if (!whitelisted) {
> - g_debug("disabling command: %s", *list);
> - qmp_disable_command(*list);
> + whitelisted = false;
> + i = 0;
> + while (ga_freeze_whitelist[i] != NULL) {
> + if (strcmp(cmd->name, ga_freeze_whitelist[i]) == 0) {
> + whitelisted = true;
> }
> - g_free(*list);
> - list++;
> + i++;
> + }
> + if (!whitelisted) {
> + g_debug("disabling command: %s", cmd->name);
> + qmp_disable_command(cmd->name);
> }
> - g_free(list_head);
> }
>
> /* [re-]enable all commands, except those explicitly blacklisted by user */
> -static void ga_enable_non_blacklisted(GList *blacklist)
> +static void ga_enable_non_blacklisted(QmpCommand *cmd, void *opaque)
> {
> - char **list_head, **list;
> -
> - list_head = list = qmp_get_command_list();
> - while (*list != NULL) {
> - if (g_list_find_custom(blacklist, *list, ga_strcmp) == NULL &&
> - !qmp_command_is_enabled(*list)) {
> - g_debug("enabling command: %s", *list);
> - qmp_enable_command(*list);
> - }
> - g_free(*list);
> - list++;
> + GList *blacklist = opaque;
> + if (g_list_find_custom(blacklist, cmd->name, ga_strcmp) == NULL &&
> + !cmd->enabled) {
qmp_command_is_enabled(cmd)
I also agree with Eric's comments about using an accessor for cmd->name to
we can continue treating QmpCommand as an opaque.
Other than that, looks good.
