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Reject promise when client returns an error
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‎CHANGELOG.md

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Original file line numberDiff line numberDiff line change
@@ -2,9 +2,11 @@
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## Unreleased
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5-
- Server requests can be treated as promesa promises.
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- Avoid blocking client responses behind client requests or notifications.
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- In certain situations the server will abort its pending sent requests to avoid
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blocking the client's messages.
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- Server requests can be treated as promesa promises.
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- Bump promesa to `10.0.594`
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## v1.8.1
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‎README.md

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Original file line numberDiff line numberDiff line change
@@ -97,11 +97,28 @@ Sending a request is similar, with `lsp4clj.server/send-request`. This method re
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response))
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```
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100-
The request object presents the same interface as `future`. It responds to `future-cancel` (which also sends `$/cancelRequest`), `realized?`, `future?`, `future-done?` and `future-cancelled?`.
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The request object presents the same interface as `future`. It responds to `realized?`, `future?`, `future-done?` and `future-cancelled?`.
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102-
If the request is cancelled, later invocations of `deref` will return `:lsp4clj.server/cancelled`.
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If you call `future-cancel` on the request object, the server will send the client a `$/cancelRequest`. `$/cancelRequest` is sent only once, although `lsp4clj.server/deref-or-cancel` or `future-cancel` can be called multiple times. After a request is cancelled, later invocations of `deref` will return `:lsp4clj.server/cancelled`.
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`$/cancelRequest` is sent only once, although `lsp4clj.server/deref-or-cancel` or `future-cancel` can be called multiple times.
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Alternatively, you can convert the request to a promesa promise, and handle it using that library's tools:
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```clojure
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(let [request (lsp4clj.server/send-request server "..." params)]
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(-> request
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(promesa/promise)
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(promesa/then (fn [response] {:result :client-success
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:value 1
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:resp response}))
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(promesa/catch (fn [ex-response] {:result :client-error
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:value 10
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:resp (ex-data ex-response)}))
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(promesa/timeout 10000 {:result :timeout
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:value 100})
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(promesa/then #(update % :value inc))))
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```
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In this case `(promesa/cancel! request)` will send `$/cancelRequest`.
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### Start and stop a server
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‎src/lsp4clj/server.clj

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Original file line numberDiff line numberDiff line change
@@ -28,6 +28,9 @@
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`(binding [*out* null-output-stream-writer]
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~@body))
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(defn- resolve-ex-data [p]
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(p/catch p (fn [ex] (or (ex-data ex) (p/rejected ex)))))
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(defprotocol IBlockingDerefOrCancel
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(deref-or-cancel [this timeout-ms timeout-val]))
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@@ -36,10 +39,10 @@
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(deref [_] (deref p))
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clojure.lang.IBlockingDeref
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(deref [_ timeout-ms timeout-val]
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(deref p timeout-ms timeout-val))
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(deref (resolve-ex-data p) timeout-ms timeout-val))
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IBlockingDerefOrCancel
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(deref-or-cancel [_ timeout-ms timeout-val]
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(let [result (deref p timeout-ms ::timeout)]
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(let [result (deref (resolve-ex-data p) timeout-ms ::timeout)]
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(if (identical? ::timeout result)
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(do (p/cancel! p)
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timeout-val)
@@ -346,14 +349,9 @@
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(if-let [{:keys [p started] :as req} (get pending-requests id)]
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(do
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(trace this trace/received-response req resp started now)
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;; We resolve the promise whether or not the client completed the
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;; request successfully. The language-server is expected to
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;; determine whether there was an error with something like:
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;; `(let [{:keys [error] :as resp} (deref-or-cancel ,,,)])`
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;; It would be somewhat more elegant to reject the promise when the
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;; client had errors, so that the language-server could use tools
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;; like `p/catch`.
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(p/resolve! p (if error resp result)))
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(if error
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(p/reject! p (ex-info "Received error response" resp))
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(p/resolve! p result)))
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(trace this trace/received-unmatched-response resp now)))
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(catch Throwable e
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(log-error-receiving this e resp))))

‎test/lsp4clj/server_test.clj

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Original file line numberDiff line numberDiff line change
@@ -385,20 +385,87 @@
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_ (server/start server nil)
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req (p/promise (server/send-request server "req" {:body "foo"}))
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client-rcvd-msg (h/assert-take output-ch)]
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(async/put! input-ch (lsp.responses/response (:id client-rcvd-msg) {:result :processed
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:value 1}))
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(is (= {:result :processed
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:value 2}
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(async/put! input-ch (lsp.responses/response (:id client-rcvd-msg) {:result "good"}))
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(is (= {:result :client-success
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:value 2
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:resp {:result "good"}}
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(-> req
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(p/timeout 1000 {:result :test-timeout
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:value 1})
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(p/then (fn [resp] {:result :client-success
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:value 1
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:resp resp}))
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(p/catch (fn [error-resp-ex] {:result :client-error
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:value 10
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:resp (ex-data error-resp-ex)}))
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(p/timeout 1000 {:result :timeout
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:value 100})
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(p/then #(update % :value inc))
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(deref))))
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(is (p/done? req))
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(is (p/resolved? req))
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(is (not (p/rejected? req)))
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(is (not (p/cancelled? req)))
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(server/shutdown server)))
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(testing "after timeout"
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(let [input-ch (async/chan 3)
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output-ch (async/chan 3)
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server (server/chan-server {:output-ch output-ch
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:input-ch input-ch})
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_ (server/start server nil)
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req (p/promise (server/send-request server "req" {:body "foo"}))]
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(is (= {:result :timeout
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:value 101}
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(-> req
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(p/then (fn [resp] {:result :client-success
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:value 1
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:resp resp}))
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(p/catch (fn [error-resp-ex] {:result :client-error
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:value 10
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:resp (ex-data error-resp-ex)}))
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(p/timeout 300 {:result :timeout
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:value 100})
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(p/then #(update % :value inc))
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(deref))))
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(is (not (p/done? req)))
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(is (not (p/resolved? req)))
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(is (not (p/rejected? req)))
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(is (not (p/cancelled? req)))
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(server/shutdown server)))
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(testing "after client error"
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(let [input-ch (async/chan 3)
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output-ch (async/chan 3)
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server (server/chan-server {:output-ch output-ch
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:input-ch input-ch})
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_ (server/start server nil)
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req (p/promise (server/send-request server "req" {:body "foo"}))
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client-rcvd-msg (h/assert-take output-ch)]
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(async/put! input-ch
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(-> (lsp.responses/response (:id client-rcvd-msg))
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(lsp.responses/error {:code 1234
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:message "Something bad"
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:data {:body "foo"}})))
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(is (= {:result :client-error
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:value 11
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:resp {:jsonrpc "2.0",
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:id 1,
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:error {:code 1234,
451+
:message "Something bad",
452+
:data {:body "foo"}}}}
453+
(-> req
454+
(p/then (fn [resp] {:result :client-success
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:value 1
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:resp resp}))
457+
(p/catch (fn [error-resp-ex] {:result :client-error
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:value 10
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:resp (ex-data error-resp-ex)}))
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(p/timeout 1000 {:result :timeout
461+
:value 100})
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(p/then #(update % :value inc))
463+
(deref))))
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(is (p/done? req))
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(is (not (p/resolved? req)))
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(is (p/rejected? req))
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(is (not (p/cancelled? req)))
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(server/shutdown server)))
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(testing "after cancellation"
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(let [input-ch (async/chan 3)
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output-ch (async/chan 3)

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