Allow combining sesman sessions of a project

- Makes cider-repls return the combination of all sesman sessions
  or those sessions with same host associated with a project
- Adds a custom vars for toggling the new functionality

Closes clojure-emacs#2946.

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 * [#3195](https://github.com/clojure-emacs/cider/issues/3195): Revert the change that resulted in `(error "Cyclic keymap inheritance")` on `cider-test-run-test`.
 
+* [#2946](https://github.com/clojure-emacs/cider/issues/2946): Add custom var `cider-combine-sesman-sessions-per-project` to allow combining all sesman sessions associated with a project, therefore allowing for jacking-in a clojure-cli clj repl and a shadow-cljs cljs repl with separate dependency management and automatically using the correct repl even though the repls are in different sesman sessions. (CAUTION: If you are using two separate sessions for local and remote development setting this var to `true` will send all evaluated commands to *both* sessions. If this is functionality you need, use `cider-combine-sesman-sessions-per-project-per-host` instead which allows combining only those sessions which have the same host associated with them.)
+
 ## 1.4.0 (2022-05-02)
 
 ## New features

cider-connection.el

@@ -61,6 +61,19 @@ available) and the matching REPL buffer."
   :safe #'booleanp
   :package-version '(cider . "0.9.0"))
 
+;;;###autoload
+(defcustom cider-merge-sessions nil
+  "Controls session combination behaviour.
+
+`:host' combines all sessions of a project associated with the same host.
+`:project' combines all sessions of a project.
+
+All other values do not combine any sessions."
+  :type 'keyword
+  :group 'cider
+  :safe #'keywordp
+  :package-version '(cider . "1.5"))
+
 (defconst cider-required-nrepl-version "0.6.0"
   "The minimum nREPL version that's known to work properly with CIDER.")
 
@@ -862,6 +875,33 @@ no linked session or there is no REPL of TYPE within the current session."
           ((listp type) (member buffer-repl-type type))
           (t (string= type buffer-repl-type)))))
 
+(defun cider--get-host-from-session (session)
+  "Returns the host associated with SESSION."
+  (plist-get (cider--gather-session-params session)
+             :host))
+
+(defun cider--make-sessions-list-with-hosts (sessions)
+  "Makes a list of SESSIONS and their hosts.
+Returns a list of the form ((session1 host1) (session2 host2) ...)."
+  (mapcar (lambda (session)
+            (list session (cider--get-host-from-session session)))
+          sessions))
+
+(defun cider--get-sessions-with-same-host (session sessions)
+  "Returns a list of SESSIONS with the same host as SESSION."
+  (mapcar #'car
+          (seq-filter (lambda (x)
+                        (string-equal (cadr x)
+                                      (cider--get-host-from-session session)))
+                      (cider--make-sessions-list-with-hosts sessions))))
+
+(defun cider--extract-connections (sessions)
+  "Returns a flattened list of all session buffers in SESSIONS."
+  (cl-reduce (lambda (x y)
+               (append x (cdr y)))
+             sessions
+             :initial-value '()))
+
 (defun cider-repls (&optional type ensure)
   "Return cider REPLs of TYPE from the current session.
 If TYPE is nil or multi, return all REPLs.  If TYPE is a list of types,
@@ -871,9 +911,24 @@ throw an error if no linked session exists."
                ((listp type)
                 (mapcar #'cider-maybe-intern type))
                ((cider-maybe-intern type))))
-        (repls (cdr (if ensure
-                        (sesman-ensure-session 'CIDER)
-                      (sesman-current-session 'CIDER)))))
+        (repls (pcase cider-merge-sessions
+                 (:host
+                  (if ensure
+                      (or (cider--extract-connections (cider--get-sessions-with-same-host
+                                                       (sesman-current-session 'CIDER)
+                                                       (sesman-current-sessions 'CIDER)))
+                          (user-error "No linked %s sessions" 'CIDER))
+                    (cider--extract-connections (cider--get-sessions-with-same-host
+                                                 (sesman-current-session 'CIDER)
+                                                 (sesman-current-sessions 'CIDER)))))
+                 (:project
+                  (if ensure
+                      (or (cider--extract-connections (sesman-current-sessions 'CIDER))
+                          (user-error "No linked %s sessions" 'CIDER))
+                    (cider--extract-connections (sesman-current-sessions 'CIDER))))
+                 (_ (cdr (if ensure
+                             (sesman-ensure-session 'CIDER)
+                           (sesman-current-session 'CIDER)))))))
     (or (seq-filter (lambda (b)
                       (cider--match-repl-type type b))
                     repls)

doc/modules/ROOT/pages/usage/managing_connections.adoc

@@ -71,11 +71,33 @@ You can add new REPLs to the current session with:
 
 A very common use-case would be to run `cider-jack-in-clj` for some project and then follow up with `cider-connect-sibling-cljs`.
 
-NOTE: Unless there are both Clojure and ClojureScript REPLs in the same session smart-dispatch commands (e.g. evaluate the code
-in the right Clojure/ClojureScript REPL, toggle between Clojure and ClojureScript REPL) won't work. A very common problem
-newcomers experience is to create a Clojure REPL and a ClojureScript REPL in separate sessions and wonder why those are not
+[NOTE]
+====
+Unless there are both Clojure and ClojureScript REPLs in the same
+session smart-dispatch commands (e.g. evaluate the code in the right
+Clojure/ClojureScript REPL, toggle between Clojure and ClojureScript REPL) won't
+work. A very common problem newcomers experience is to create a Clojure REPL and
+a ClojureScript REPL in separate sessions and wonder why those are not
 interacting properly with one another.
 
+In the case of using separate config files for the clj and cljs dependencies
+(e.g. clj dependencies in `deps.edn` and cljs dependencies in `shadow-cljs.edn`)
+it is currently impossible to group those two repls in the same session.
+However, this can be worked around by setting
+`cider-combine-sesman-sessions-per-project` to a non-nil value. This has the
+effect of dispatching to all relevant repls (i.e. all clj repls for a `.clj`
+buffer) instead of just those associated with the current session. It is
+recommended to set this as needed on a per-project basis in `.dir-locals.el`.
+
+The downside of `cider-combine-sesman-sessions-per-project` is that dispatching
+to separate local and remote sessions is no longer possible since all
+project-associated sessions essentially become a single big session. Should this
+behaviour be desired `cider-combine-sesman-sessions-per-project-per-host` can be
+used instead. This var takes precedence over
+`cider-combine-sesman-sessions-per-project` and only combines those sessions
+which have the same host associated with them.
+====
+
 === Session Life-Cycle Management
 
 Session life-cycle management commands live on the https://github.com/vspinu/sesman[Sesman] keymap (kbd:[C-c C-s])

test/cider-connection-tests.el

@@ -272,6 +272,90 @@
                         (expect (cider-repls) :to-equal (list bb2 bb1))
                         (expect (cider-repls 'cljs) :to-equal (list bb2)))))))))))))
 
+  (describe "when multiple sessions exist and cider-merge-sessions is set to :project"
+    (it "always returns all connections associated with a project"
+      (let ((proj-dir (expand-file-name "/tmp/proj-dir"))
+            (cider-merge-sessions :project))
+        (let ((default-directory proj-dir))
+          (with-repl-buffer ses-name 'clj bb1
+            (with-repl-buffer ses-name 'cljs bb2
+              (with-repl-buffer ses-name2 'clj b1
+                (with-repl-buffer ses-name2 'cljs b2
+
+                  (expect (cider-repls) :to-have-same-items-as (list b2 b1 bb2 bb1))
+
+                  (switch-to-buffer bb1)
+                  (expect (cider-repls) :to-have-same-items-as (list b2 b1 bb2 bb1))
+
+                  ;; follows type arguments
+                  (expect (cider-repls 'clj) :to-have-same-items-as (list b1 bb1))
+                  (expect (cider-repls 'cljs) :to-have-same-items-as (list b2 bb2))
+
+                  (switch-to-buffer bb2)
+                  ;; follows file type
+                  (with-temp-buffer
+                    (setq major-mode 'clojure-mode)
+                    (expect (cider-repls) :to-have-same-items-as (list b2 b1 bb2 bb1))
+                    (expect (cider-repls 'clj) :to-have-same-items-as (list b1 bb1)))
+
+                  (with-temp-buffer
+                    (setq major-mode 'clojurescript-mode)
+                    (expect (cider-repls) :to-have-same-items-as (list b2 b1 bb2 bb1))
+                    (expect (cider-repls 'cljs) :to-have-same-items-as (list b2 bb2))))))))))
+    (it "only returns the connections of the active project"
+      (let ((a-dir (expand-file-name "/tmp/a-dir"))
+            (b-dir (expand-file-name "/tmp/b-dir"))
+            (cider-merge-sessions :project))
+        (let ((default-directory a-dir))
+          (with-repl-buffer ses-name 'clj bb1
+            (with-repl-buffer ses-name 'cljs bb2
+              (let ((default-directory b-dir))
+                (with-repl-buffer ses-name2 'clj b1
+                  (with-repl-buffer ses-name2 'cljs b2
+
+                    (expect (cider-repls) :to-have-same-items-as (list b2 b1))
+
+                    (switch-to-buffer bb1)
+                    (expect (cider-repls) :to-have-same-items-as (list bb2 bb1))
+
+                    ;; follows type arguments
+                    (expect (cider-repls 'clj) :to-have-same-items-as (list bb1))
+                    (expect (cider-repls 'cljs) :to-have-same-items-as (list bb2))
+
+                    (switch-to-buffer bb2)
+                    ;; follows file type
+                    (let ((default-directory b-dir))
+                      (with-temp-buffer
+                        (setq major-mode 'clojure-mode)
+                        (expect (cider-repls) :to-have-same-items-as (list b2 b1))
+                        (expect (cider-repls 'clj) :to-have-same-items-as (list b1))))
+
+                    (let ((default-directory a-dir))
+                      (with-temp-buffer
+                        (setq major-mode 'clojurescript-mode)
+                        (expect (cider-repls) :to-have-same-items-as (list bb2 bb1))
+                        (expect (cider-repls 'cljs) :to-have-same-items-as (list bb2)))))))))))))
+
+  (describe "when multiple sessions exist and cider-combine-merge-sessions is set to :host"
+    (before-each
+      (spy-on 'cider--gather-session-params :and-call-fake (lambda (session)
+                                                             (if (string-equal (car session) "local")
+                                                                  '(:host "localhost")
+                                                                '(:host "remotehost")))))
+    (it "returns only the sessions associated with the current session's host"
+      (let ((cider-merge-sessions :host)
+            (local-session "local")
+            (remote-session "remote")
+            (proj-dir (expand-file-name "/tmp/proj-dir")))
+        (let ((default-directory proj-dir))
+          (with-repl-buffer local-session 'clj l1
+            (with-repl-buffer local-session 'clj l2
+              (with-repl-buffer remote-session 'clj r1
+                (switch-to-buffer r1)
+                (expect (cider-repls) :to-have-same-items-as (list r1))
+                (switch-to-buffer l1)
+                (expect (cider-repls) :to-have-same-items-as (list l1 l2)))))))))
+
   (describe "killed buffers"
     (it "do not show up in it"
       (let ((default-directory (expand-file-name "/tmp/some-dir")))