[TAM] Granular counter subscription

doc/TAM/Granular-Counter-Subscription.md

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+#  Telemetry Granular Counter Subscription
+-------------------------------------------------------------------------------
+ Title       | Telemetry Granular Counter Subscription
+-------------|-----------------------------------------------------------------
+ Authors     | Jason Bos, Cisco
+ Status      | In review
+ Type        | Standards track
+ Created     | 2023-01-11 - Initial Draft
+ SAI-Version | 1.12
+-------------------------------------------------------------------------------
+
+
+## 1.0  Introduction
+
+This spec enhances the existing TAM (Telemetry and Monitoring) spec to add granular counter subscription.
+
+The TAM API  allows for predefined telemetry groups, like SAI_TAM_TELEMETRY_TYPE_SWITCH or SAI_TAM_TELEMETRY_TYPE_PORT. This provides extensibility to the API only to define new fixed collections. When collecting counters, all supported counters for the relevant objects are reported.
+
+However, the user may wish to enable telemetry for a more limited set of counters, selected at runtime. For example, a user may wish to receive only port byte counters, or queue watermarks. Limiting the scope of the telemetry collection permits a device to generate counters samples faster than possible when all counters are collected, and fit many more samples into each network packet, allowing a higher rate of delivery.
+
+In this mode, the collector may require a meaningful identifier for a counter, which identifies both the object as well as the specific counter on the object.
+Depending on the report type, this may be carried directly in the report itself. Or it may be delivered separately, for example as an enterprise-specific
+information element ID in an IPFIX template set.
+
+## 2.0 Configuration
+
+The subscription is represented by an object of SAI_TAM_COUNTER_SUBSCRIPTION. The creation of this object will indicate that a specific counter should be monitored.
+
+```c
+typedef enum _sai_tam_counter_subscription_attr_t
+{
+    /**
+     * @brief Start of Attributes
+     */
+    SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_START,
+
+    /**
+     * @brief TAM telemetry type object
+     *
+     * @type sai_object_id_t
+     * @flags MANDATORY_ON_CREATE | CREATE_ONLY
+     * @objects SAI_OBJECT_TYPE_TAM
+     */
+    SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_TEL_TYPE = SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_START,
+
+    /**
+     * @brief Subscribed object
+     *
+     * @type sai_object_id_t
+     * @flags MANDATORY_ON_CREATE | CREATE_ONLY
+     */
+    SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_OBJECT_ID,
+
+    /**
+     * @brief Subscribed stat enum
+     *
+     * @type sai_uint32_t
+     * @flags MANDATORY_ON_CREATE | CREATE_ONLY
+     */
+    SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_STAT_ID,
+
+     /**
+     * @brief Telemetry label
+     *
+     * Label to identify the subscribed counter in telemetry reports.
+     *
+     * @type sai_uint64_t
+     * @flags CREATE_ONLY
+     * @default 0
+     */
+    SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_LABEL,
+```
+
+The attribute SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_LABEL configures the application counter ID.
+
+
+## 3 Configuration example
+
+```c
+
+// Example: Create a bulk report object
+sai_attr_list[0].id = SAI_TAM_REPORT_ATTR_TYPE;
+sai_attr_list[0].value.s32 = SAI_TAM_REPORT_TYPE_PROTO;
+
+sai_attr_list[1].id = SAI_TAM_REPORT_ATTR_REPORT_MODE;
+sai_attr_list[1].value.s32 = SAI_TAM_REPORT_MODE_BULK;
+
+attr_count = 2;
+
+sai_create_tam_report_fn(
+   &sai_tam_report_obj,
+   switch_id,
+   attr_count,
+   sai_attr_list);
+
+// Example: Create telemetry type object to collect object stats
+sai_attr_list[0].id = SAI_TAM_TEL_TYPE_ATTR_TAM_TELEMETRY_TYPE;
+sai_attr_list[0].value.u32 = SAI_TAM_TELEMETRY_TYPE_OBJECT_STAT;
+
+sai_attr_list[1].id = SAI_TAM_TEL_TYPE_ATTR_REPORT_ID;
+sai_attr_list[1].value.oid = sai_tam_report_obj;
+
+attr_count = 2;
+sai_create_tam_tel_type_fn(
+    &sai_tam_tel_type_obj,
+    switch_id,
+    attr_count,
+    sai_attr_list);
+
+// Example: Create counter subscription(s) to collect queue length and watermark
+sai_attr_list[0].id = SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_TEL_TYPE;
+sai_attr_list[0].value.u32 = sai_tam_tel_type_obj;
+
+sai_attr_list[1].id = SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_OBJECT_ID;
+sai_attr_list[1].value.oid = sai_queue_obj;
+
+sai_attr_list[2].id = SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_STAT_ID;
+sai_attr_list[2].value.u32 = SAI_QUEUE_STAT_CURR_OCCUPANCY_BYTES;
+
+sai_attr_list[3].id = SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_LABEL;
+sai_attr_list[3].value.u64 = 1;
+
+attr_count = 4;
+sai_create_tam_counter_subscription_fn(
+    &sai_tam_subscription_obj1,
+    switch_id,
+    attr_count,
+    sai_attr_list);
+
+sai_attr_list[0].id = SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_TEL_TYPE;
+sai_attr_list[0].value.u32 = sai_tam_tel_type_obj;
+
+sai_attr_list[1].id = SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_OBJECT_ID;
+sai_attr_list[1].value.oid = sai_queue_obj;
+
+sai_attr_list[2].id = SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_STAT_ID;
+sai_attr_list[2].value.u32 = SAI_QUEUE_STAT_WATERMARK_BYTES;
+
+sai_attr_list[3].id = SAI_TAM_COUNTER_SUBSCRIPTION_ATTR_LABEL;
+sai_attr_list[3].value.u64 = 2;
+
+attr_count = 4;
+sai_create_tam_counter_subscription_fn(
+    &sai_tam_subscription_obj2,
+    switch_id,
+    attr_count,
+    sai_attr_list);
+
+// Example: Create Telemetry object
+sai_attr_list[0].id = SAI_TAM_TELEMETRY_ATTR_TAM_TYPE_LIST;
+sai_attr_list[0].value.objlist.count = 1
+sai_attr_list[0].value.objlist.list[0] = sai_tam_tel_type_obj;
+
+sai_attr_list[1].id = SAI_TAM_TELEMETRY_ATTR_COLLECTOR_LIST
+sai_attr_list[1].value.objlist.count = 1;
+sai_attr_list[1].value.objlist.list[0] = collector_obj;
+
+attr_count = 2;
+sai_create_tam_telemetry_fn(
+    &sai_tam_telemetry_obj,
+    switch_id,
+    attr_count,
+    sai_attr_list);
+
+// Example: Create TAM object and bind to monitored objects:
+
+sai_attr_list[0].id = SAI_TAM_ATTR_TAM_TELEMETRY_OBJECTS_LIST;
+sai_attr_list[0].value.objlist.count = 1;
+sai_attr_list[0].value.objlist.list[0] = sai_tam_telemetry_obj;
+
+sai_attr_list[1].id = SAI_TAM_ATTR_TAM_BIND_POINT_TYPE_LIST;
+sai_attr_list[1].value.objlist.count = 1;
+sai_attr_list[1].value.objlist.list[0] = SAI_TAM_BIND_POINT_TYPE_SWITCH;
+
+attr_count = 2;
+sai_create_tam_fn(
+    &sai_tam_obj,
+    switch_id,
+    attr_count,
+    sai_attr_list);
+
+// Example: Attach the TAM to the switch
+
+sai_attr.id = SAI_SWITCH_ATTR_TAM_OBJECT_ID;
+sai_attr.value.oid = sai_tam_obj;
+
+sai_set_queue_attribute_fn(
+    sai_switch_obj,
+    sai_attr);
+```
+
+## 4 Example data export format
+
+Counter subscription is independent of a specific report format. The format of the report is determined by the report object. In case of protobuf report format, a potential data layout is below:
+
+```
+message CounterSample {
+    required uint64 timestamp = 1 [(telemetry_options).is_timestamp = true];
+    repeated uint64 counter_values = 2;
+}
+
+message CounterSampleList {
+    // Counter labels in the order the values will appear in each sample
+    repeated uint64 counter_labels = 1;
+    repeated CounterSample samples = 2;
+}
+```
+