initial

include/grpc/census.h

@@ -46,11 +46,12 @@ extern "C" {
 
 /* Identify census functionality that can be enabled via census_initialize(). */
 enum census_functions {
-  CENSUS_NONE = 0,    /* Do not enable census. */
-  CENSUS_TRACING = 1, /* Enable census tracing. */
-  CENSUS_STATS = 2,   /* Enable Census stats collection. */
-  CENSUS_CPU = 4,     /* Enable Census CPU usage collection. */
-  CENSUS_ALL = CENSUS_TRACING | CENSUS_STATS | CENSUS_CPU
+  CENSUS_NONE = 0,       /* Do not enable census. */
+  CENSUS_TRACING = 1,    /* Enable distributed tracing. */
+  CENSUS_STATS = 2,      /* Enable stats collection. */
+  CENSUS_CPU = 4,        /* Enable CPU usage collection. */
+  CENSUS_ACTIVE_OPS = 8, /* Trace Active operations. */
+  CENSUS_ALL = CENSUS_TRACING | CENSUS_STATS | CENSUS_CPU | CENSUS_ACTIVE_OPS
 };
 
 /* Shutdown and startup census subsystem. The 'functions' argument should be
@@ -100,26 +101,149 @@ int census_context_deserialize(const char *buffer, census_context **context);
  * future census calls will result in undefined behavior. */
 void census_context_destroy(census_context *context);
 
-/* Start a new logical tracing "operation". The operation ends when
- * census_trace_end_op() is called. */
-void census_trace_start_op(census_context *context);
-+ service method start time,
-    peer ? +sampled ?
-
-                    /* End a tracing operation. Must be matched with an earlier
-                     * census_start_op().
-                     */
-    void
-    census_trace_end_op(census_context *context);
-+ status
-
-    /* Insert a trace record into the trace stream. The record consists of an
-     * arbitrary size buffer, the size of which is provided in 'n'. */
-    void
-    census_trace_print(census_context *context, const char *buffer, size_t n);
-
-census_active_ops_as_html() + struct or char *query ops
-    census_sampled_ops_as_html()
+/* Distributed traces can have a number of options. */
+enum census_trace_mask_values {
+  CENSUS_TRACE_MASK_NONE = 0,       /* Default, empty flags */
+  CENSUS_TRACE_MASK_IS_SAMPLED = 1, /* RPC tracing enabled for this context. */
+};
+
+/** Get the current trace mask associated with this context. The value returned
+    will be the logical or of census_trace_mask_values values. */
+int census_trace_mask(const census_context *context);
+
+/* The concept of "operation" is a fundamental concept for Census. An
+   operation is a logical representation of a action in a RPC-using system. It
+   is most typically used to represent a single RPC, or a significant sub-part
+   thereof (e.g. a single logical "read" RPC to a distributed storage system
+   might do several other actions in parallel, from looking up metadata
+   indices to making requests of other services - each of these could be a
+   sub-operation with the larger RPC operation. Census uses operations for the
+   following:
+
+   CPU accounting: If enabled, census will measure the thread CPU time
+   consumed between operation start and end times.
+
+   Active operations: Census will maintain information on all currently
+   active operations.
+
+   Distributed tracing: Each operation serves as a logical trace span.
+
+   Stats collection: Stats are broken down operation (e.g. latency
+   breakdown for each service/method combination).
+
+   The following functions serve to delineate the start and stop points for
+   each logical operation. */
+/**
+   Start a client rpc operation. This function will create a new context. If
+   the context argument is non-null, then the new context will inherit all
+   its properties, with the following changes:
+   - create a new operation ID for the new context, marking it as a child of
+     the previous operation.
+   - use the new RPC service/method/peer information for tracing and stats
+     collection purposes, rather than those from the original context
+   - if trace_mask is non-zero, update the trace mask entries associated with
+     the original context.
+
+   If the context argument is NULL, then a new root context is created.  This
+   is particularly important for tracing purposes (the trace spans generated
+   will be unassociated with any other trace spans, except those
+   downstream). Whatever it's value, the trace_mask will be used for tracing
+   operations associated with the new context.
+
+   @param context The base context. Can be NULL.
+   @param service RPC service name. On some systems, may include other
+   parts of RPC identification (e.g. host on gRPC systems).
+   @param method RPC method name
+   @param peer RPC peer
+   @param trace_mask An or of census_trace_mask_values values
+   @param start_time If NULL, the time of function call is used as the
+   start time for the operation. If non-NULL, then the time should be in the
+   past, when the operation was deemed to have started. This is used when
+   the other information used as arguments is not yet available.
+
+   @return A new census context.
+ */
+census_context *census_start_client_rpc_op(census_context *context,
+                                           const char *service,
+                                           const char *method, const char *peer,
+                                           int trace_mask,
+                                           gpr_timespec *start_time);
+
+/**
+   Indicate the start of a server rpc operation, updating the current
+   context (which should have been created from census_context_deserialize()
+   (as passed from the client side of the RPC operation) or census_start_op().
+   - if trace_mask is non-zero, update the trace mask entries associated with
+     the original context.
+
+   @param context The base context. Cannot be NULL.
+   @param service RPC service name. On some systems, may include other
+   parts of RPC identification (e.g. host on gRPC systems).
+   @param method RPC method name
+   @param peer RPC peer
+   @param trace_mask An or of census_trace_mask_values values
+   @param start_time If NULL, the time of function call is used as the
+   start time for the operation. If non-NULL, then the time should be in the
+   past, when the operation was deemed to have started. This is used when
+   the other information used as arguments is not yet available.
+ */
+void census_start_server_rpc_op(census_context *context, const char *service,
+                                const char *method, const char *peer,
+                                int trace_mask, gpr_timespec *start_time);
+
+/**
+   Start a new, non-RPC census operation. In general, this function works very
+   similarly to census_start_client_rpc_op, with the primary differennce being
+   the abscence of peer information, and the replacement of service and method
+   names with the more general family/name. If the context argument is
+   non-null, then the new context will inherit all its properties, with the
+   following changes:
+   - create a new operation ID for the new context, marking it as a child of
+     the previous operation.
+   - use the family and name information for tracing and stats collection
+     purposes, rather than those from the original context
+   - if trace_mask is non-zero, update the trace mask entries associated with
+     the original context.
+
+   If the context argument is NULL, then a new root context is created.  This
+   is particularly important for tracing purposes (the trace spans generated
+   will be unassociated with any other trace spans, except those
+   downstream). Whatever it's value, the trace_mask will be used for tracing
+   operations associated with the new context.
+
+   @param context The base context. Can be NULL.
+   @param family Family name to associate with the trace
+   @param name Name within family to associated with traces/stats
+   @param trace_mask An or of census_trace_mask_values values
+   @param start_time If NULL, the time of function call is used as the
+   start time for the operation. If non-NULL, then the time should be in the
+   past, when the operation was deemed to have started. This is used when
+   the other information used as arguments is not yet available.
+
+   @return A new census context.
+ */
+census_context *census_start_op(census_context *context, const char *family,
+                                const char *name, int trace_mask,
+                                gpr_timespec *start_time);
+
+/** End a tracing operation. Must be matched with an earlier
+ * census_start_*_op*() call. */
+void census_trace_end_op(census_context *context, int status);
+
+/** Insert a trace record into the trace stream. The record consists of an
+ * arbitrary size buffer, the size of which is provided in 'n'. */
+void census_trace_print(census_context *context, const char *buffer, size_t n);
+
+/** Retrieve active ops as a proto. Note that since we don't have proto
+    manipulation available in the grpc core yet, arguments etc. are left
+    unspecified for now. */
+void census_get_active_ops_as_proto(/* pointer to proto */);
+
+/** Retrieve all active trace records as a proto. Note that since we don't
+    have proto manipulation available in the grpc core yet, arguments etc. are
+    left unspecified for now. This function will clear existing trace
+    records. */
+void census_get_trace_as_proto(/* pointer to proto */);
 
 #ifdef __cplusplus
 }