Add "/api/jobs/history" API.

* src/cuirass/database.scm (db-get-jobs-history): New procedure.
* src/cuirass/http.scm (jobs-history->json-object): New procedure.
(url-handler): New "/api/jobs/history" route.
* tests/database.scm ("db-get-jobs-history"): New test.

doc/cuirass.texi

@@ -932,6 +932,49 @@ The job name, as a string.
 
 @end table
 
+@subsection Jobs history
+
+The history of jobs across the last evaluations of a given
+specification can be optained with the API "/api/jobs/history".
+
+This request accepts three mandatory parameters.
+
+@table @code
+@item specification
+The specification name. This parameter is @emph{mandatory}.
+
+@item names
+Filter query result to jobs which names are part of the given
+@code{names} list, a comma separated list of job names.  This
+parameter is @emph{mandatory}.
+
+@item nr
+Limit query result to nr elements. This parameter is @emph{mandatory}.
+
+@end table
+
+For example, to ask for the history of @code{emacs.x86_64-linux} and
+@code{emacs-minimal.x86_64-linux} jobs of the @code{master}
+specification over the last 10 evaluations:
+
+@example
+$ curl "http://localhost:8080/api/jobs/history?spec=master&names=emacs.x86_64-linux,emacs-minimal.x86_64-linux&nr=10"
+@end example
+
+The nominal output is a JSON array which objects have the following field:
+
+@table @code
+@item evaluation
+The unique evaluation id.
+
+@item checkouts
+The evaluation checkouts as a JSON array.
+
+@item name
+The jobs list for this evaluation, as a JSON array.
+
+@end table
+
 @subsection Latest builds
 
 The list of latest builds can be obtained with the API
@@ -1117,12 +1160,18 @@ This integer field references the evaluation identifier from the
 @code{Evaluations} table, indicating to which evaluation this job
 belongs.
 
-@item builds
+@item build
 This integer field references the build id from the @code{Builds}
 table, corresponding to this job.
 
+@item status
+This integer field holds the build status of the above build.  The
+goal of this duplication is to avoid expensive joins between the Jobs
+and Builds table.
+
 @item system
-This text field holds the system name of the derivation.
+This text field holds the system name of the above build.  This field
+is duplicated for the same reason as the above status field.
 
 @end table
 

src/cuirass/database.scm

@@ -69,6 +69,7 @@
             db-get-time-since-previous-eval
             db-get-build-percentages
             db-get-jobs
+            db-get-jobs-history
             db-register-builds
             db-update-build-status!
             db-update-build-worker!
@@ -737,6 +738,50 @@ ORDER BY Jobs.name")
                          (#:name . ,name))
                        jobs))))))))
 
+(define* (db-get-jobs-history names #:key spec limit)
+  "Return the list of jobs from Jobs table which name is a member of the given
+NAMES list, for the last LIMIT evaluations of SPEC specification."
+  (define (format-names names)
+    (format #f "{~a}" (string-join names ",")))
+
+  (with-db-worker-thread db
+    (let ((query "
+SELECT name, evaluation, build, status FROM Jobs
+WHERE Jobs.evaluation IN (SELECT id FROM Evaluations
+WHERE specification = :spec AND status = 0
+ORDER BY id DESC LIMIT :nr)
+AND Jobs.name = ANY(:names);")
+          (params
+           `((#:spec . ,spec)
+             (#:names . ,(format-names names)))))
+      (let loop ((rows (exec-query/bind-params db query params))
+                 (evaluations '()))
+        (match rows
+          (() (sort evaluations
+                    (lambda (a b)
+                      (let ((eval (cut assq-ref <> #:evaluation)))
+                        (> (eval a) (eval b))))))
+          (((name evaluation build status)
+            . rest)
+           (loop rest
+                 (let* ((eval (find (lambda (e)
+                                      (eq? (assq-ref e #:evaluation)
+                                           (string->number evaluation)))
+                                    evaluations))
+                        (jobs (and eval
+                                   (assq-ref eval #:jobs)))
+                        (job `((#:name . ,name)
+                               (#:build . ,(string->number build))
+                               (#:status . ,(string->number status)))))
+                   (if eval
+                       (begin
+                         (assq-set! eval #:jobs (cons job jobs))
+                         evaluations)
+                       (cons `((#:evaluation . ,(string->number evaluation))
+                               (#:checkouts . ,(db-get-checkouts evaluation))
+                               (#:jobs . ,(list job)))
+                             evaluations))))))))))
+
 (define (db-register-builds jobs eval-id specification)
   (define (new-outputs? outputs)
     (let ((new-outputs

src/cuirass/http.scm

@@ -173,6 +173,18 @@
     (#:systems . ,(list->vector
                    (specification-systems spec)))))
 
+(define (jobs-history->json-object history)
+  "Turn HISTORY into a representation suitable for 'json->scm'."
+  (object->json-string
+   (list->vector
+    (map (lambda (eval)
+           `((#:evaluation . ,(assq-ref eval #:evaluation))
+             (#:checkouts . ,(list->vector
+                              (assq-ref eval #:checkouts)))
+             (#:jobs . ,(list->vector
+                         (assq-ref eval #:jobs)))))
+         history))))
+
 (define (handle-build-request build-id)
   "Retrieve build identified by BUILD-ID over the database and convert it to
 hydra format. Return #f is not build was found."
@@ -705,6 +717,27 @@ into a specification record and return it."
                                         (cut string-split <> #\,)))
                              ,@params)))))
            (respond-json-with-error 500 "Parameter not defined!"))))
+    (('GET "api" "jobs" "history")
+     (let* ((params (request-parameters request))
+            (names (and=> (assq-ref params 'names)
+                          (cut string-split <> #\,)))
+            (spec (assq-ref params 'spec))
+            (limit (assq-ref params 'nr)))
+       (cond
+        ((not (and names spec limit))
+         (respond-json-with-error 500 "Parameter not defined"))
+        ((> limit 100)
+         (respond-json-with-error 500 "Maximum limit exceeded"))
+        (else
+         (catch 'json-invalid
+           (lambda ()
+             (respond-json
+              (jobs-history->json-object
+               (db-get-jobs-history names
+                                    #:spec spec
+                                    #:limit limit))))
+           (lambda _
+             (respond-json-with-error 500 "Invalid body")))))))
     (('GET "api" "evaluation")
      (let* ((params (request-parameters request))
             (id (assq-ref params 'id)))

tests/database.scm

@@ -235,6 +235,16 @@ timestamp, checkouttime, evaltime) VALUES ('guix', 0, 0, 0, 0);")
                            #:derivation)
                  "/test.drv"))))
 
+  (test-assert "db-get-jobs-history"
+    (begin
+      (db-set-evaluation-status 4 (evaluation-status succeeded))
+      (match (db-get-jobs-history '("test")
+                                  #:spec "guix"
+                                  #:limit 2)
+        ((eval)
+         (and (eq? (assq-ref eval #:evaluation) 4)
+              (eq? (length (assq-ref eval #:jobs)) 1))))))
+
   (test-assert "db-update-build-status!"
     (db-update-build-status! "/test.drv"
                              (build-status failed)))
@@ -342,7 +352,7 @@ timestamp, checkouttime, evaltime) VALUES ('guix', 0, 0, 0, 0);")
     (db-get-evaluations-id-max "foo"))
 
   (test-equal "db-get-latest-evaluations"
-    1
+    4
     (match (db-get-latest-evaluations)
       ((eval)
        (assq-ref eval #:evaluation))))