/
middleware.clj
184 lines (172 loc) · 8.85 KB
/
middleware.clj
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
(ns nrepl.middleware
(:refer-clojure :exclude [comparator])
(:require
[clojure.set :as set]
[nrepl.misc :as misc]
[nrepl.transport :as transport]
[nrepl.version :as version]))
(defn- var-name
[^clojure.lang.Var v]
(str (.ns v) \/ (.sym v)))
(defn- wrap-conj-descriptor
[descriptor-map h]
(fn [{:keys [op descriptors] :as msg}]
(h (if-not (= op "describe")
msg
(assoc msg :descriptors (merge descriptor-map descriptors))))))
(defn set-descriptor!
"Sets the given [descriptor] map as the ::descriptor metadata on
the provided [middleware-var], after assoc'ing in the var's
fully-qualified name as the descriptor's \"implemented-by\" value."
[middleware-var descriptor]
(let [descriptor (-> descriptor
(assoc :implemented-by (-> middleware-var var-name symbol))
(update-in [:expects] (fnil conj #{}) "describe"))]
(alter-meta! middleware-var assoc ::descriptor descriptor)
(alter-var-root middleware-var #(comp (partial wrap-conj-descriptor
{middleware-var descriptor}) %))))
(defn- safe-version
[m]
(into {} (filter (fn [[_ v]] (or (number? v) (string? v))) m)))
(defn- java-version
[]
(let [version-string (System/getProperty "java.version")
version-seq (re-seq #"\d+" version-string)
version-map (if (<= 3 (count version-seq))
(zipmap [:major :minor :incremental :update] version-seq)
{})]
(assoc version-map :version-string version-string)))
(defn wrap-describe
[h]
(fn [{:keys [op descriptors verbose? transport] :as msg}]
(if (= op "describe")
(transport/send transport (misc/response-for msg
(merge
(when-let [aux (reduce
(fn [aux {:keys [describe-fn]}]
(if describe-fn
(merge aux (describe-fn msg))
aux))
nil
(vals descriptors))]
{:aux aux})
{:ops (let [ops (apply merge (map :handles (vals descriptors)))]
(if verbose?
ops
(zipmap (keys ops) (repeat {}))))
:versions {:nrepl (safe-version version/version)
:clojure (safe-version
(assoc *clojure-version* :version-string (clojure-version)))
:java (safe-version (java-version))}
:status :done})))
(h msg))))
(set-descriptor! #'wrap-describe
{:handles {"describe"
{:doc "Produce a machine- and human-readable directory and documentation for the operations supported by an nREPL endpoint."
:requires {}
:optional {"verbose?" "Include informational detail for each \"op\"eration in the return message."}
:returns {"ops" "Map of \"op\"erations supported by this nREPL endpoint"
"versions" "Map containing version maps (like *clojure-version*, e.g. major, minor, incremental, and qualifier keys) for values, component names as keys. Common keys include \"nrepl\" and \"clojure\"."
"aux" "Map of auxiliary data contributed by all of the active nREPL middleware via :describe-fn functions in their descriptors."}}}})
;; eliminate implicit expectation of "describe" handler; this is the only
;; special case introduced by the conj'ing of :expects "describe" by set-descriptor!
(alter-meta! #'wrap-describe update-in [::descriptor :expects] disj "describe")
(defn- dependencies
[set start dir]
(let [ops (start dir)
deps (set/select
(comp seq (partial set/intersection ops) :handles)
set)]
(when (deps start)
(throw (IllegalArgumentException.
(format "Middleware %s depends upon itself via %s"
(:implemented-by start)
dir))))
(concat ops
(mapcat #(dependencies set % dir) deps))))
(defn- comparator
[{a-requires :requires a-expects :expects a-handles :handles}
{b-requires :requires b-expects :expects b-handles :handles}]
(or (->> (into {} [[[a-requires b-handles] -1]
[[a-expects b-handles] 1]
[[b-requires a-handles] 1]
[[b-expects a-handles] -1]])
(map (fn [[sets ret]]
(and (seq (apply set/intersection sets)) ret)))
(some #{-1 1}))
0))
(defn- extend-deps
[middlewares]
(let [descriptor #(-> % meta ::descriptor)
middlewares (concat middlewares
(->> (map descriptor middlewares)
(mapcat (juxt :expects :requires))
(mapcat identity)
(filter var?)))]
(doseq [m (remove descriptor middlewares)]
(binding [*out* *err*]
(printf "[WARNING] No nREPL middleware descriptor in metadata of %s, see nrepl.middleware/set-descriptor!" m)
(println)))
(let [middlewares (set (for [m middlewares]
(-> (descriptor m)
;; only conj'ing m here to support direct reference to
;; middleware dependencies in :expects and :requires,
;; e.g. interruptable-eval's dep on
;; nrepl.middleware.print/wrap-print
(update-in [:handles] (comp set #(conj % m) keys))
(assoc :implemented-by m))))]
(set (for [m middlewares]
(reduce
#(update-in % [%2] into (dependencies middlewares % %2))
m #{:expects :requires}))))))
(defn- topologically-sort
"Topologically sorts the given middlewares according to the comparator,
with the added heuristic that any middlewares that have no dependencies
will be sorted toward the end."
[komparator stack]
(let [stack (vec stack)
;; using indexes into the above vector as the vertices in the
;; graph algorithm, will translate back into middlewares at
;; the end.
vertices (range (count stack))
edges (for [i1 vertices
i2 (range i1)
:let [x (komparator (stack i1) (stack i2))]
:when (not= 0 x)]
(if (neg? x) [i1 i2] [i2 i1]))
;; the trivial vertices have no connections, and we pull them
;; out here so we can make sure they get put on the end
trivial-vertices (remove (set (apply concat edges)) vertices)]
(loop [sorted-vertices []
remaining-edges edges
remaining-vertices (remove (set trivial-vertices) vertices)]
(if (seq remaining-vertices)
(let [non-initials (->> remaining-edges
(map second)
(set))
next-vertex (->> remaining-vertices
(remove non-initials)
(first))]
(if next-vertex
(recur (conj sorted-vertices next-vertex)
(remove #((set %) next-vertex) remaining-edges)
(remove #{next-vertex} remaining-vertices))
;; Cycle detected! Have to actually assemble a cycle so we
;; can throw a useful error.
(let [start (first remaining-vertices)
step (into {} remaining-edges)
cycle (->> (iterate step start)
(rest)
(take-while (complement #{start}))
(cons start))
data {:cycle (map stack cycle)}]
(throw (ex-info
"Unable to satisfy nREPL middleware ordering requirements!"
data)))))
(map stack (concat sorted-vertices trivial-vertices))))))
(defn linearize-middleware-stack
[middlewares]
(->> middlewares
extend-deps
(topologically-sort comparator)
(map :implemented-by)))