feat: implement background thread, collector config, batching

This commit is contained in:
Simon Cruanes 2022-03-21 15:01:41 -04:00
parent 3d89103ca6
commit 124ba09b2b
No known key found for this signature in database
GPG key ID: EBFFF6F283F3A2B4
4 changed files with 363 additions and 73 deletions

View file

@ -2,5 +2,5 @@
(library
(name opentelemetry_client_ocurl)
(public_name opentelemetry-client-ocurl)
(libraries opentelemetry curl ocaml-protoc))
(libraries opentelemetry curl ocaml-protoc threads mtime mtime.clock.os))

View file

@ -23,42 +23,82 @@ let set_mutex ~lock ~unlock : unit =
lock_ := lock;
unlock_ := unlock
module Config = struct
type t = {
debug: bool;
url: string;
batch_traces: int option;
batch_metrics: int option;
thread: bool;
}
let pp out self =
let ppiopt = Format.pp_print_option Format.pp_print_int in
let {debug; url; batch_traces; batch_metrics; thread} = self in
Format.fprintf out "{@[ debug=%B;@ url=%S;@ \
batch_traces=%a;@ batch_metrics=%a;@ thread=%B @]}"
debug url ppiopt batch_traces ppiopt batch_metrics
thread
let make
?(debug= !debug_)
?(url= get_url())
?(batch_traces=Some 400)
?(batch_metrics=None)
?(thread=true)
() : t =
{ debug; url; batch_traces; batch_metrics; thread; }
end
(* critical section for [f()] *)
let[@inline] with_lock_ f =
!lock_();
Fun.protect ~finally:!unlock_ f
let _init = lazy (
let[@inline] with_mutex_ m f =
Mutex.lock m;
Fun.protect ~finally:(fun () -> Mutex.unlock m) f
let _init_curl = lazy (
Curl.global_init Curl.CURLINIT_GLOBALALL;
at_exit Curl.global_cleanup;
)
module Backend() : Opentelemetry.Collector.BACKEND = struct
let() = Lazy.force _init
type error = [
| `Status of int * Opentelemetry.Proto.Status.status
| `Failure of string
]
(* TODO: use Curl.Multi, etc. *)
let report_err_ = function
| `Failure msg ->
Format.eprintf "@[<2>opentelemetry: export failed: %s@]@." msg
| `Status (code, status) ->
Format.eprintf "@[<2>opentelemetry: export failed with@ http code=%d@ status %a@]@."
code Proto.Status.pp_status status
module type CURL = sig
val send : path:string -> decode:(Pbrt.Decoder.t -> 'a) -> string -> ('a, error) result
val cleanup : unit -> unit
end
(* create a curl client *)
module Curl() : CURL = struct
open Opentelemetry.Proto
let() = Lazy.force _init_curl
let encoder = Pbrt.Encoder.create()
let buf_res = Buffer.create 256
let rand_ = Random.State.make_self_init()
(* TODO: use Curl.Multi, etc. instead? *)
(* http client *)
let curl : Curl.t = Curl.init ()
let cleanup () = Curl.cleanup curl
open Opentelemetry.Proto
open Opentelemetry.Collector
type error = [
| `Status of int * Status.status
| `Failure of string
]
(* TODO: use Curl multi *)
(* send the content to the remote endpoint/path *)
let send_ ~path ~decode (bod:string) : ('a, error) result =
let send ~path ~decode (bod:string) : ('a, error) result =
Curl.reset curl;
if !debug_ then Curl.set_verbose curl true;
Curl.set_url curl (!url ^ path);
@ -100,48 +140,52 @@ module Backend() : Opentelemetry.Collector.BACKEND = struct
~code:(Int32.of_int code) ~message:(Bytes.unsafe_of_string msg) () in
Error(`Status (code, status))
with e -> Error (`Failure (Printexc.to_string e))
end
let report_err_ = function
| `Failure msg ->
Format.eprintf "@[<2>opentelemetry: export failed: %s@]@." msg
| `Status (code, status) ->
Format.eprintf "@[<2>opentelemetry: export failed with@ http code=%d@ status %a@]@."
code Status.pp_status status
module type PUSH = sig
type elt
val push : elt -> unit
val is_empty : unit -> bool
val is_big_enough : unit -> bool
val pop_iter_all : (elt -> unit) -> unit
end
let send_trace : Trace_service.export_trace_service_request sender = {
send=fun tr ~over ~ret ->
let@() = with_lock_ in
if !debug_ then Format.eprintf "send trace %a@." Trace_service.pp_export_trace_service_request tr;
Pbrt.Encoder.reset encoder;
Trace_service.encode_export_trace_service_request tr encoder;
begin match
send_ ~path:"/v1/traces" ~decode:(fun _ -> ())
(Pbrt.Encoder.to_string encoder)
with
| Ok () -> ()
| Error err -> report_err_ err
end;
over();
ret()
(* queue of fixed size *)
module FQueue : sig
type 'a t
val create : dummy:'a -> int -> 'a t
val size : _ t -> int
val push : 'a t -> 'a -> unit
val pop_iter_all : 'a t -> ('a -> unit) -> unit
end = struct
type 'a t = {
arr: 'a array;
mutable i: int;
}
let send_metrics : Metrics_service.export_metrics_service_request sender = {
send=fun m ~over ~ret ->
let@() = with_lock_ in
if !debug_ then Format.eprintf "send metrics %a@." Metrics_service.pp_export_metrics_service_request m;
Pbrt.Encoder.reset encoder;
Metrics_service.encode_export_metrics_service_request m encoder;
begin
match
send_ ~path:"/v1/metrics" ~decode:(fun _ -> ())
(Pbrt.Encoder.to_string encoder);
with
| Ok () -> ()
| Error err -> report_err_ err
end;
over();
ret()
}
let create ~dummy n : _ t =
assert (n >= 1);
{ arr=Array.make n dummy;
i=0;
}
let[@inline] size self = self.i
let push (self:_ t) x : unit =
assert (self.i < Array.length self.arr);
self.arr.(self.i) <- x;
self.i <- 1 + self.i
let pop_iter_all (self: _ t) f =
for j=0 to self.i-1 do
f self.arr.(j)
done;
self.i <- 0
end
(* generate random IDs *)
module Gen_ids() = struct
let rand_ = Random.State.make_self_init()
let rand_bytes_8 () : bytes =
let@() = with_lock_ in
@ -171,15 +215,225 @@ module Backend() : Opentelemetry.Collector.BACKEND = struct
b
end
let setup_ () =
let module B = Backend() in
(** Callback for when an event is properly sent to the collector *)
type over_cb = unit -> unit
(** An emitter. This is used by {!Backend} below to forward traces/metrics/…
from the program to whatever collector client we have. *)
module type EMITTER = sig
open Opentelemetry.Proto
val push_trace : Trace.resource_spans list -> over:over_cb -> unit
val push_metrics : Metrics.resource_metrics list -> over:over_cb -> unit
val cleanup : unit -> unit
end
type 'a push = (module PUSH with type elt = 'a)
type on_full_cb = (unit -> unit)
(* make a "push" object, along with a setter for a callback to call when
it's ready to emit a batch *)
let mk_push (type a) ?batch () : (module PUSH with type elt = a) * (on_full_cb -> unit) =
let on_full: on_full_cb ref = ref ignore in
let push =
match batch with
| None ->
let r = ref None in
let module M = struct
type elt = a
let is_empty () = !r == None
let is_big_enough () = !r != None
let push x =
r := Some x; !on_full()
let pop_iter_all f = Option.iter f !r; r := None
end in
(module M : PUSH with type elt = a)
| Some n ->
let q = FQueue.create ~dummy:(Obj.magic 0) (2 * n) in
let module M = struct
type elt = a
let is_empty () = FQueue.size q = 0
let is_big_enough () = FQueue.size q >= n
let push x =
FQueue.push q x;
if FQueue.size q > n then (
!on_full()
)
let pop_iter_all f = FQueue.pop_iter_all q f
end in
(module M : PUSH with type elt = a)
in
push, ((:=) on_full)
let mk_emitter ~(config:Config.t) () : (module EMITTER) =
let open Proto in
let continue = ref true in
let ((module E_trace) : (Trace.resource_spans list * over_cb) push), on_trace_full =
mk_push ?batch:config.batch_traces () in
let ((module E_metrics) : (Metrics.resource_metrics list * over_cb) push), on_metrics_full =
mk_push ?batch:config.batch_metrics () in
let encoder = Pbrt.Encoder.create() in
let emit_metrics (module C:CURL) (l:(Metrics.resource_metrics list*over_cb) list) =
Pbrt.Encoder.reset encoder;
let resource_metrics =
List.fold_left (fun acc (l,_) -> List.rev_append l acc) [] l in
Metrics_service.encode_export_metrics_service_request
(Metrics_service.default_export_metrics_service_request
~resource_metrics ())
encoder;
begin match
C.send ~path:"/v1/metrics" ~decode:(fun _ -> ())
(Pbrt.Encoder.to_string encoder)
with
| Ok () -> ()
| Error err -> report_err_ err
end;
(* signal completion *)
List.iter (fun (_,over) -> over()) l;
in
let emit_traces (module C: CURL) (l:(Trace.resource_spans list * over_cb) list) =
Pbrt.Encoder.reset encoder;
let resource_spans =
List.fold_left (fun acc (l,_) -> List.rev_append l acc) [] l in
Trace_service.encode_export_trace_service_request
(Trace_service.default_export_trace_service_request ~resource_spans ())
encoder;
begin match
C.send ~path:"/v1/traces" ~decode:(fun _ -> ())
(Pbrt.Encoder.to_string encoder)
with
| Ok () -> ()
| Error err -> report_err_ err
end;
(* signal completion *)
List.iter (fun (_,over) -> over()) l;
in
if config.thread then (
begin
let m = Mutex.create() in
set_mutex ~lock:(fun () -> Mutex.lock m) ~unlock:(fun () -> Mutex.unlock m);
end;
let module C = Curl() in
let m = Mutex.create() in
let cond = Condition.create() in
let last_wakeup = ref (Mtime_clock.now()) in
(* TODO: move this into config *)
let batch_timeout() : bool =
let elapsed = Mtime.span (Mtime_clock.now()) !last_wakeup in
Mtime.Span.compare elapsed Mtime.Span.(200 * ms) >= 0
in
let emit_metrics ?(force=false) () : bool =
if (force && not (E_metrics.is_empty())) ||
(not force && E_metrics.is_big_enough ()) then (
let batch = ref [] in
E_metrics.pop_iter_all (fun l -> batch := l :: !batch);
emit_metrics (module C) !batch;
true
) else false
in
let emit_traces ?(force=false) () : bool =
if (force && not (E_trace.is_empty())) ||
(not force && E_trace.is_big_enough ()) then (
let batch = ref [] in
E_trace.pop_iter_all (fun l -> batch := l :: !batch);
emit_traces (module C) !batch;
true
) else false
in
let bg_thread () =
while !continue do
if emit_metrics () then ()
else if emit_traces () then ()
else (
(* wait *)
let@ () = with_mutex_ m in
Condition.wait cond m;
)
done;
(* flush remaining events *)
ignore (emit_traces ~force:true () : bool);
ignore (emit_metrics ~force:true () : bool);
C.cleanup();
in
let _: Thread.t = Thread.create bg_thread () in
let wakeup () =
last_wakeup := Mtime_clock.now();
with_mutex_ m (fun () -> Condition.signal cond)
in
(* wake up if a batch is full *)
on_metrics_full wakeup;
on_trace_full wakeup;
let module M = struct
let push_trace e ~over =
E_trace.push (e,over);
if batch_timeout() then wakeup()
let push_metrics e ~over =
E_metrics.push (e,over);
if batch_timeout() then wakeup()
let cleanup () =
continue := false;
with_mutex_ m (fun () -> Condition.broadcast cond)
end in
(module M)
) else (
assert false
)
module Backend(Arg : sig val config : Config.t end)()
: Opentelemetry.Collector.BACKEND
= struct
include Gen_ids()
include (val mk_emitter ~config:Arg.config ())
open Opentelemetry.Proto
open Opentelemetry.Collector
let send_trace : Trace.resource_spans list sender = {
send=fun l ~over ~ret ->
let@() = with_lock_ in
if !debug_ then Format.eprintf "send spans %a@." (Format.pp_print_list Trace.pp_resource_spans) l;
push_trace l ~over;
ret()
}
let send_metrics : Metrics.resource_metrics list sender = {
send=fun m ~over ~ret ->
let@() = with_lock_ in
if !debug_ then Format.eprintf "send metrics %a@." (Format.pp_print_list Metrics.pp_resource_metrics) m;
push_metrics m ~over;
ret()
}
end
let setup_ ~(config:Config.t) () =
debug_ := config.debug;
let module B = Backend(struct let config=config end)() in
Opentelemetry.Collector.backend := Some (module B);
B.cleanup
let setup() =
let cleanup = setup_() in
let setup ?(config=Config.make()) () =
let cleanup = setup_ ~config () in
at_exit cleanup
let with_setup f =
let cleanup = setup_() in
let with_setup ?(config=Config.make()) f =
let cleanup = setup_ ~config () in
Fun.protect ~finally:cleanup f

View file

@ -11,8 +11,50 @@ val set_url : string -> unit
or "OTEL_EXPORTER_OTLP_ENDPOINT" if set. *)
val set_mutex : lock:(unit -> unit) -> unlock:(unit -> unit) -> unit
(** Set a lock/unlock pair to protect the critical sections
of {!Opentelemetry.Collector.BACKEND} *)
val setup : unit -> unit
(** Setup endpoint. This modifies {!Opentelemetry.Collector.backend}. *)
module Config : sig
type t = {
debug: bool;
val with_setup : (unit -> 'a) -> 'a
url: string;
(** Url of the endpoint. Default is "http://localhost:4318",
or "OTEL_EXPORTER_OTLP_ENDPOINT" if set. *)
batch_traces: int option;
(** Batch traces? If [Some i], then this produces batches of (at most)
[i] items. If [None], there is no batching.
Note that traces and metrics are batched separately.
Default [Some 400].
*)
batch_metrics: int option;
(** Batch metrics? If [Some i], then this produces batches of (at most)
[i] items. If [None], there is no batching.
Note that traces and metrics are batched separately.
Default [None].
*)
thread: bool;
(** Is there a background thread? Default [true] *)
}
val make :
?debug:bool -> ?url:string ->
?batch_traces:int option ->
?batch_metrics:int option ->
?thread:bool ->
unit -> t
(** Make a configuration *)
val pp : Format.formatter -> t -> unit
end
val setup : ?config:Config.t -> unit -> unit
(** Setup endpoint. This modifies {!Opentelemetry.Collector.backend}.
@param config configuration to use *)
val with_setup : ?config:Config.t -> (unit -> 'a) -> 'a

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@ -79,9 +79,9 @@ module Collector = struct
(** Collector client interface. *)
module type BACKEND = sig
val send_trace : Trace_service.export_trace_service_request sender
val send_trace : Trace.resource_spans list sender
val send_metrics : Metrics_service.export_metrics_service_request sender
val send_metrics : Metrics.resource_metrics list sender
val rand_bytes_16 : unit -> bytes
(** Generate 16 bytes of random data *)
@ -102,18 +102,12 @@ module Collector = struct
let send_trace (l:Trace.resource_spans list) ~over ~ret =
match !backend with
| None -> over(); ret()
| Some (module B) ->
let ev = Trace_service.default_export_trace_service_request
~resource_spans:l () in
B.send_trace.send ev ~over ~ret
| Some (module B) -> B.send_trace.send l ~over ~ret
let send_metrics (l:Metrics.resource_metrics list) ~over ~ret =
match !backend with
| None -> over(); ret()
| Some (module B) ->
let ev = Metrics_service.default_export_metrics_service_request
~resource_metrics:l () in
B.send_metrics.send ev ~over ~ret
| Some (module B) -> B.send_metrics.send l ~over ~ret
let rand_bytes_16 () =
match !backend with