[v4] plugins/syscall: Added a table-like summary output

Added a table-like output which contains the total number of calls
for each used syscall along with the number of errors that occurred.

Per-call tracing is still available through supplying the argument
``print`` to the plugin.

Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
---
v3 -> v4: Added a missing ``static`` that was causing a compilation 
          error. Otherwise, everything else is left in place.
 tests/plugin/syscall.c | 98 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 93 insertions(+), 5 deletions(-)

Mahmoud Mandour <ma.mandourr@gmail.com> writes:

> Added a table-like output which contains the total number of calls
> for each used syscall along with the number of errors that occurred.
>
> Per-call tracing is still available through supplying the argument
> ``print`` to the plugin.
>
> Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>

Queued to plugins/next, thanks.

> ---
> v3 -> v4: Added a missing ``static`` that was causing a compilation 
>           error. Otherwise, everything else is left in place.
>  tests/plugin/syscall.c | 98 +++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 93 insertions(+), 5 deletions(-)
>
> diff --git a/tests/plugin/syscall.c b/tests/plugin/syscall.c
> index 53ee2ab6c4..6dd71092e1 100644
> --- a/tests/plugin/syscall.c
> +++ b/tests/plugin/syscall.c
> @@ -16,32 +16,120 @@
>  
>  QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
>  
> +typedef struct {
> +    int64_t num;
> +    int64_t calls;
> +    int64_t errors;
> +} SyscallStats;
> +
> +static GMutex lock;
> +static GHashTable *statistics;
> +
> +static SyscallStats *get_or_create_entry(int64_t num)
> +{
> +    SyscallStats *entry =
> +        (SyscallStats *) g_hash_table_lookup(statistics, GINT_TO_POINTER(num));
> +
> +    if (!entry) {
> +        entry = g_new0(SyscallStats, 1);
> +        entry->num = num;
> +        g_hash_table_insert(statistics, GINT_TO_POINTER(num), (gpointer) entry);
> +    }
> +
> +    return entry;
> +}
> +
>  static void vcpu_syscall(qemu_plugin_id_t id, unsigned int vcpu_index,
>                           int64_t num, uint64_t a1, uint64_t a2,
>                           uint64_t a3, uint64_t a4, uint64_t a5,
>                           uint64_t a6, uint64_t a7, uint64_t a8)
>  {
> -    g_autofree gchar *out = g_strdup_printf("syscall #%" PRIi64 "\n", num);
> -    qemu_plugin_outs(out);
> +    if (statistics) {
> +        SyscallStats *entry;
> +        g_mutex_lock(&lock);
> +        entry = get_or_create_entry(num);
> +        entry->calls++;
> +        g_mutex_unlock(&lock);
> +    } else {
> +        g_autofree gchar *out = g_strdup_printf("syscall #%" PRIi64 "\n", num);
> +        qemu_plugin_outs(out);
> +    }
>  }
>  
>  static void vcpu_syscall_ret(qemu_plugin_id_t id, unsigned int vcpu_idx,
>                               int64_t num, int64_t ret)
> +{
> +    if (statistics) {
> +        SyscallStats *entry;
> +
> +        g_mutex_lock(&lock);
> +        /* Should always return an existent entry. */
> +        entry = get_or_create_entry(num);
> +        if (ret < 0) {
> +            entry->errors++;
> +        }
> +        g_mutex_unlock(&lock);
> +    } else {
> +        g_autofree gchar *out;
> +        out = g_strdup_printf("syscall #%" PRIi64 " returned -> %" PRIi64 "\n",
> +                num, ret);
> +        qemu_plugin_outs(out);
> +    }
> +}
> +
> +static void print_entry(gpointer val, gpointer user_data)
>  {
>      g_autofree gchar *out;
> -    out = g_strdup_printf("syscall #%" PRIi64 " returned -> %" PRIi64 "\n",
> -            num, ret);
> +    SyscallStats *entry = (SyscallStats *) val;
> +    int64_t syscall_num = entry->num;
> +    out = g_strdup_printf(
> +        "%-13" PRIi64 "%-6" PRIi64 " %" PRIi64 "\n",
> +        syscall_num, entry->calls, entry->errors);
>      qemu_plugin_outs(out);
>  }
>  
> +static gint comp_func(gconstpointer ea, gconstpointer eb)
> +{
> +    SyscallStats *ent_a = (SyscallStats *) ea;
> +    SyscallStats *ent_b = (SyscallStats *) eb;
> +
> +    return ent_a->calls > ent_b->calls ? -1 : 1;
> +}
> +
>  /* ************************************************************************* */
> +static void plugin_exit(qemu_plugin_id_t id, void *p)
> +{
> +    if (!statistics) {
> +        return;
> +    }
> +
> +    g_mutex_lock(&lock);
> +    GList *entries = g_hash_table_get_values(statistics);
> +    entries = g_list_sort(entries, comp_func);
> +    qemu_plugin_outs("syscall no.  calls  errors\n");
>  
> -static void plugin_exit(qemu_plugin_id_t id, void *p) {}
> +    g_list_foreach(entries, print_entry, NULL);
> +
> +    g_list_free(entries);
> +    g_hash_table_destroy(statistics);
> +    g_mutex_unlock(&lock);
> +}
>  
>  QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
>                                             const qemu_info_t *info,
>                                             int argc, char **argv)
>  {
> +    if (argc == 0) {
> +        statistics = g_hash_table_new_full(NULL, g_direct_equal, NULL, g_free);
> +    } else {
> +        for (int i = 0; i < argc; i++) {
> +            if (g_strcmp0(argv[i], "print") != 0) {
> +                fprintf(stderr, "unsupported argument: %s\n", argv[i]);
> +                return -1;
> +            }
> +        }
> +    }
> +
>      qemu_plugin_register_vcpu_syscall_cb(id, vcpu_syscall);
>      qemu_plugin_register_vcpu_syscall_ret_cb(id, vcpu_syscall_ret);
>      qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);