#lang racket/base
(require "structs.rkt" racket/list)
;; Format a percent number, possibly doing the division too. If we do the
;; division, then be careful: if we're dividing by zero, then make the result
;; zero. This is useful if the total time is zero because we didn't see any
;; activity (for example, the profiled code is just doing a `sleep'), in which
;; case all times will be 0.
(provide format-percent)
(define format-percent
(case-lambda
[(percent) (define p (inexact->exact (round (* percent 1000))))
(format "~a.~a%" (quotient p 10) (modulo p 10))]
[(x y) (format-percent (if (zero? y) 0 (/ x y)))]))
(provide format-source)
(define (format-source src)
(if src
(format "~a:~a"
(srcloc-source src)
(if (srcloc-line src)
(format "~a:~a" (srcloc-line src) (srcloc-column src))
(format "#~a" (srcloc-position src))))
"(unknown source)"))
;; Hide a node if its self time is smaller than the self threshold *and* all of
;; its edges are below the sub-node threshold too -- this avoids confusing
;; output where a node does not have an entry but appears as a caller/callee.
(provide get-hidden)
(define (get-hidden profile hide-self% hide-subs%)
(define self% (or hide-self% 0))
(define subs% (or hide-subs% 0))
(define total-time (profile-total-time profile))
(define (hide? node)
(define (hide-sub? get-subs edge-sub edge-sub-time)
(define %s
(map (λ (edge)
(define total (node-total (edge-sub edge)))
(if (zero? total) 0 (/ (edge-sub-time edge) total)))
(get-subs node)))
(subs% . >= . (apply max %s)))
(and (self% . >= . (/ (node-self node) total-time))
(hide-sub? node-callees edge-callee edge-caller-time)
(hide-sub? node-callers edge-caller edge-callee-time)))
(cond [(and (<= self% 0) (<= subs% 0)) '()]
[(zero? total-time) (profile-nodes profile)]
[else (filter hide? (profile-nodes profile))]))
;; A topological sort of nodes, starting from node `root' (which will be given
;; as the special *-node). The result is a list of node lists, each one
;; corresponds to one level. Conceptually, the root node is always the only
;; item in the first level, so it is not included in the result. This is done
;; by assigning layers to nodes in a similar way to section 9.1 of "Graph
;; Drawing: Algorithms for the Visualization of Graphs" by Tollis, Di Battista,
;; Eades, and Tamassia. It uses a technique similar to the one described in
;; section 9.4 for removing cycles in the input graph, but improved by the fact
;; that we have weights on input/output edges (this is the only point that is
;; specific to the fact that it's a profiler graph). Note that this is useful
;; for a graphical rendering of the results, but it's also useful to sort the
;; results in a way that makes more sense.
(provide topological-sort)
(define (topological-sort root)
;; Make `nodes+io-times' map a node to an mcons of total input and total
;; output times ignoring edges to/from the *-node and self edges, the order
;; is the reverse of how we scan the graph
(define (get-node+io node)
(define (sum node-callers/lees edge-caller/lee edge-callee/ler-time)
(for/fold ([sum 0]) ([e (in-list (node-callers/lees node))])
(define n (edge-caller/lee e))
(if (or (eq? n node) (eq? n root)) sum
(+ sum (edge-callee/ler-time e)))))
(cons node (mcons (sum node-callers edge-caller edge-callee-time)
(sum node-callees edge-callee edge-caller-time))))
(define nodes+io-times
(let loop ([todo (list root)] [r '()])
(if (pair? todo)
(let* ([cur (car todo)] [todo (cdr todo)]
[r (if (eq? cur root) r (cons (get-node+io cur) r))])
(loop (append todo ; append new things in the end, so it's a BFS
(filter-map (λ (e)
(define lee (edge-callee e))
(and (not (memq lee todo))
(not (assq lee r))
lee))
(node-callees cur)))
r))
;; note: the result does not include the root node
r)))
;; Now create a linear order similar to the way section 9.4 describes, except
;; that this uses the total caller/callee times to get an even better
;; ordering (also, look for sources and sinks in every step). Note that the
;; list we scan is in reverse order.
(define acyclic-order
(let loop ([todo nodes+io-times] [rev-left '()] [right '()])
;; heuristic for best sources: the ones with the lowest intime/outtime
(define (best-sources)
(let loop ([todo todo] [r '()] [best #f])
(if (null? todo)
r
(let* ([1st (car todo)]
[rest (cdr todo)]
[ratio (/ (mcar (cdr 1st)) (mcdr (cdr 1st)))])
(if (or (not best) (ratio . < . best))
(loop rest (list 1st) ratio)
(loop rest (if (ratio . > . best) r (cons 1st r)) best))))))
(if (pair? todo)
(let* ([sinks (filter (λ (x) (zero? (mcdr (cdr x)))) todo)]
[todo (remq* sinks todo)]
[sources (filter (λ (x) (zero? (mcar (cdr x)))) todo)]
;; if we have no sources and sinks, use the heuristic
[sources (if (and (null? sinks) (null? sources))
(best-sources) sources)]
[todo (remq* sources todo)]
[sinks (map car sinks)]
[sources (map car sources)])
;; remove the source and sink times from the rest
(for* ([nodes (in-list (list sources sinks))]
[n (in-list nodes)])
(for ([e (in-list (node-callees n))])
(define x (assq (edge-callee e) todo))
(when x
(set-mcar! (cdr x) (- (mcar (cdr x)) (edge-callee-time e)))))
(for ([e (in-list (node-callers n))])
(define x (assq (edge-caller e) todo))
(when x
(set-mcdr! (cdr x) (- (mcdr (cdr x)) (edge-caller-time e))))))
(loop todo (append (reverse sources) rev-left) (append sinks right)))
;; all done, get the order
(append (reverse rev-left) right))))
;; We're done, so make `t' map nodes to their callers with only edges that
;; are consistent with this ordering
(define t
(let ([t (make-hasheq)])
(let loop ([nodes acyclic-order])
(when (pair? nodes)
(define ler (car nodes))
(define rest (cdr nodes))
(unless (hash-ref t ler #f) (hash-set! t ler '()))
(for ([e (in-list (node-callees ler))])
(define lee (edge-callee e))
(when (memq lee rest) ; only consistent edges
;; note that we connect each pair of nodes at most once, and
;; never a node with itself
(hash-set! t lee (cons ler (hash-ref t lee '())))))
(loop rest)))
t))
;; finally, assign layers using the simple method from section 9.1: sources
;; are at 0, and other nodes are placed at one layer after their parents
(define height 0)
(for ([node (in-list acyclic-order)])
(let loop ([node node])
(define x (hash-ref t node))
(if (number? x)
x
(let ([max (add1 (for/fold ([m -1]) ([ler (in-list x)])
(max m (loop ler))))])
(when (max . > . height) (set! height max))
(hash-set! t node max)
max))))
(define layers (make-vector (add1 height) '()))
(for ([node (in-list acyclic-order)])
(unless (eq? node root) ; filter out the root
(define l (hash-ref t node))
(vector-set! layers l (cons node (vector-ref layers l)))))
;; in almost all cases, the root is the full first layer (in a few cases it
;; can be there with another node, eg (* -> A 2-> B 3-> A)), but be safe and
;; look for any empty layer
(filter pair? (vector->list layers)))
;; gets a list of thread-id and data for that thread beginning with the
;; millisecond count, and returns a similar list where the samples begin with
;; the time spent for that sample. The time spent is taken as half of the two
;; touching ranges; for example, if there are three samples showing snapshot
;; times of 10, 20, 60, then the middle one is assumed to have a time of 25.
;; For the first and last samples, the time is twice the half of the single
;; touching range -- with this example, this would be 10 for the first and 40
;; for the last. If there is a thread with just one sample, it is dropped.
(provide get-times)
(define (get-times samples)
(cond
;; nothing to do
[(null? samples) '()]
;; throw out a single sample
[(null? (cdr samples)) '()]
[else (let loop ([samples samples]
[prevs (cons #f (map car samples))]
[r '()])
(if (null? samples)
(reverse r)
(let* ([prev (car prevs)]
[cur (caar samples)]
[data (cdar samples)]
[prevs (cdr prevs)]
[samples (cdr samples)]
[next (and (pair? samples) (caar samples))])
(loop samples prevs
(cons (cons (if next
;; not the last: there must be a next
(if prev (/ (- next prev) 2) (- next cur))
;; last one: there must be a prev
(- cur prev))
data)
r)))))]))
(module+ test
(require rackunit)
(check-equal? (get-times '())
'())
(check-equal? (get-times '([10 a]))
'())
(check-equal? (get-times '([10 a] [20 b]))
'([10 a] [10 b]))
(check-equal? (get-times '([10 a] [20 b] [60 c]))
'([10 a] [25 b] [40 c]))
(check-equal? (get-times '([10 a] [20 b] [30 c] [40 d]))
'([10 a] [10 b] [10 c] [10 d]))
(check-equal? (get-times '([10 a] [20 b] [60 c] [80 d]))
'([10 a] [25 b] [30 c] [20 d])))