;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2015, 2016 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2015, 2016, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2016 Chris Marusich <cmmarusich@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
#:use-module (guix store)
#:use-module (guix records)
#:use-module (guix profiles)
+ #:use-module (guix discovery)
+ #:use-module (guix combinators)
+ #:use-module (guix channels)
+ #:use-module (guix describe)
#:use-module (guix sets)
#:use-module (guix ui)
+ #:use-module ((guix utils) #:select (source-properties->location))
+ #:use-module (guix modules)
#:use-module (gnu packages base)
#:use-module (gnu packages bash)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-35)
#:use-module (ice-9 vlist)
#:use-module (ice-9 match)
+ #:autoload (ice-9 pretty-print) (pretty-print)
#:export (service-extension
service-extension?
+ service-extension-target
+ service-extension-compute
service-type
service-type?
service-type-extensions
service-type-compose
service-type-extend
+ service-type-default-value
+ service-type-description
+ service-type-location
+
+ %service-type-path
+ fold-service-types
+ lookup-service-types
service
service?
service-kind
- service-parameters
+ service-value
+ service-parameters ;deprecated
+ simple-service
modify-services
service-back-edges
+ instantiate-missing-services
fold-services
service-error?
+ missing-value-service-error?
+ missing-value-service-error-type
+ missing-value-service-error-location
missing-target-service-error?
missing-target-service-error-service
missing-target-service-error-target-type
ambiguous-target-service-error-target-type
system-service-type
+ provenance-service-type
boot-service-type
cleanup-service-type
activation-service-type
activation-service->script
%linux-bare-metal-service
+ special-files-service-type
+ extra-special-file
etc-service-type
etc-directory
setuid-program-service-type
profile-service-type
firmware-service-type
+ gc-root-service-type
%boot-service
%activation-service
- etc-service
-
- file-union)) ;XXX: for lack of a better place
+ etc-service))
;;; Comment:
;;;
;;; A service type describe how its instances extend instances of other
;;; service types. For instance, some services extend the instance of
;;; ACCOUNT-SERVICE-TYPE by providing it with accounts and groups to create;
-;;; others extend DMD-ROOT-SERVICE-TYPE by passing it instances of
-;;; <dmd-service>.
+;;; others extend SHEPHERD-ROOT-SERVICE-TYPE by passing it instances of
+;;; <shepherd-service>.
;;;
;;; When applicable, the service type defines how it can itself be extended,
;;; by providing one procedure to compose extensions, and one procedure to
(target service-extension-target) ;<service-type>
(compute service-extension-compute)) ;params -> params
+(define &no-default-value
+ ;; Value used to denote service types that have no associated default value.
+ '(no default value))
+
(define-record-type* <service-type> service-type make-service-type
service-type?
(name service-type-name) ;symbol (for debugging)
;; Extend the services' own parameters with the extension composition.
(extend service-type-extend ;list of Any -> parameters
- (default #f)))
+ (default #f))
+
+ ;; Optional default value for instances of this type.
+ (default-value service-type-default-value ;Any
+ (default &no-default-value))
+
+ ;; Meta-data.
+ (description service-type-description ;string
+ (default #f))
+ (location service-type-location ;<location>
+ (default (and=> (current-source-location)
+ source-properties->location))
+ (innate)))
(define (write-service-type type port)
(format port "#<service-type ~a ~a>"
(set-record-type-printer! <service-type> write-service-type)
+(define %distro-root-directory
+ ;; Absolute file name of the module hierarchy.
+ (dirname (search-path %load-path "guix.scm")))
+
+(define %service-type-path
+ ;; Search path for service types.
+ (make-parameter `((,%distro-root-directory . "gnu/services")
+ (,%distro-root-directory . "gnu/system"))))
+
+(define (all-service-modules)
+ "Return the default set of service modules."
+ (cons (resolve-interface '(gnu services))
+ (all-modules (%service-type-path)
+ #:warn warn-about-load-error)))
+
+(define* (fold-service-types proc seed
+ #:optional
+ (modules (all-service-modules)))
+ "For each service type exported by one of MODULES, call (PROC RESULT). SEED
+is used as the initial value of RESULT."
+ (fold-module-public-variables (lambda (object result)
+ (if (service-type? object)
+ (proc object result)
+ result))
+ seed
+ modules))
+
+(define lookup-service-types
+ (let ((table
+ (delay (fold-service-types (lambda (type result)
+ (vhash-consq (service-type-name type)
+ type result))
+ vlist-null))))
+ (lambda (name)
+ "Return the list of services with the given NAME (a symbol)."
+ (vhash-foldq* cons '() name (force table)))))
+
;; Services of a given type.
(define-record-type <service>
- (service type parameters)
+ (make-service type value)
service?
(type service-kind)
- (parameters service-parameters))
+ (value service-value))
+
+(define-syntax service
+ (syntax-rules ()
+ "Return a service instance of TYPE. The service value is VALUE or, if
+omitted, TYPE's default value."
+ ((_ type value)
+ (make-service type value))
+ ((_ type)
+ (%service-with-default-value (current-source-location)
+ type))))
+
+(define (%service-with-default-value location type)
+ "Return a instance of service type TYPE with its default value, if any. If
+TYPE does not have a default value, an error is raised."
+ ;; TODO: Currently this is a run-time error but with a little bit macrology
+ ;; we could turn it into an expansion-time error.
+ (let ((default (service-type-default-value type)))
+ (if (eq? default &no-default-value)
+ (let ((location (source-properties->location location)))
+ (raise
+ (condition
+ (&missing-value-service-error (type type) (location location))
+ (&message
+ (message (format #f (G_ "~a: no value specified \
+for service of type '~a'")
+ (location->string location)
+ (service-type-name type)))))))
+ (service type default))))
+
+(define-condition-type &service-error &error
+ service-error?)
+
+(define-condition-type &missing-value-service-error &service-error
+ missing-value-service-error?
+ (type missing-value-service-error-type)
+ (location missing-value-service-error-location))
+
+
+\f
+;;;
+;;; Helpers.
+;;;
+
+(define service-parameters
+ ;; Deprecated alias.
+ service-value)
+(define (simple-service name target value)
+ "Return a service that extends TARGET with VALUE. This works by creating a
+singleton service type NAME, of which the returned service is an instance."
+ (let* ((extension (service-extension target identity))
+ (type (service-type (name name)
+ (extensions (list extension)))))
+ (service type value)))
(define-syntax %modify-service
(syntax-rules (=>)
service)
((_ svc (kind param => exp ...) clauses ...)
(if (eq? (service-kind svc) kind)
- (let ((param (service-parameters svc)))
+ (let ((param (service-value svc)))
(service (service-kind svc)
(begin exp ...)))
(%modify-service svc clauses ...)))))
(define-syntax modify-services
(syntax-rules ()
- "Modify the services listed in SERVICES according to CLAUSES. Each clause
-must have the form:
+ "Modify the services listed in SERVICES according to CLAUSES and return
+the resulting list of services. Each clause must have the form:
(TYPE VARIABLE => BODY)
(service-type (name 'system)
(extensions '())
(compose identity)
- (extend system-derivation)))
-
-(define (compute-boot-script _ mexps)
- (mlet %store-monad ((gexps (sequence %store-monad mexps)))
- (gexp->file "boot"
- ;; Clean up and activate the system, then spawn dmd.
- #~(begin #$@gexps))))
+ (extend system-derivation)
+ (description
+ "Build the operating system top-level directory, which in
+turn refers to everything the operating system needs: its kernel, initrd,
+system profile, boot script, and so on.")))
+
+(define (compute-boot-script _ gexps)
+ ;; Reverse GEXPS so that extensions appear in the boot script in the right
+ ;; order. That is, user extensions would come first, and extensions added
+ ;; by 'essential-services' (e.g., running shepherd) are guaranteed to come
+ ;; last.
+ (gexp->file "boot"
+ ;; Clean up and activate the system, then spawn shepherd.
+ #~(begin #$@(reverse gexps))))
(define (boot-script-entry mboot)
"Return, as a monadic value, an entry for the boot script in the system
(return `(("boot" ,boot)))))
(define boot-service-type
- ;; The service of this type is extended by being passed gexps as monadic
- ;; values. It aggregates them in a single script, as a monadic value, which
- ;; becomes its 'parameters'. It is the only service that extends nothing.
+ ;; The service of this type is extended by being passed gexps. It
+ ;; aggregates them in a single script, as a monadic value, which becomes its
+ ;; value.
(service-type (name 'boot)
(extensions
(list (service-extension system-service-type
boot-script-entry)))
- (compose append)
- (extend compute-boot-script)))
+ (compose identity)
+ (extend compute-boot-script)
+ (description
+ "Produce the operating system's boot script, which is spawned
+by the initrd once the root file system is mounted.")))
(define %boot-service
;; The service that produces the boot script.
(service boot-service-type #t))
+\f
+;;;
+;;; Provenance tracking.
+;;;
+
+(define (object->pretty-string obj)
+ "Like 'object->string', but using 'pretty-print'."
+ (call-with-output-string
+ (lambda (port)
+ (pretty-print obj port))))
+
+(define (channel->code channel)
+ "Return code to build CHANNEL, ready to be dropped in a 'channels.scm'
+file."
+ `(channel (name ',(channel-name channel))
+ (url ,(channel-url channel))
+ (branch ,(channel-branch channel))
+ (commit ,(channel-commit channel))))
+
+(define (channel->sexp channel)
+ "Return an sexp describing CHANNEL. The sexp is _not_ code and is meant to
+be parsed by tools; it's potentially more future-proof than code."
+ `(channel (name ,(channel-name channel))
+ (url ,(channel-url channel))
+ (branch ,(channel-branch channel))
+ (commit ,(channel-commit channel))))
+
+(define (provenance-file channels config-file)
+ "Return a 'provenance' file describing CHANNELS, a list of channels, and
+CONFIG-FILE, which can be either #f or a <local-file> containing the OS
+configuration being used."
+ (scheme-file "provenance"
+ #~(provenance
+ (version 0)
+ (channels #+@(if channels
+ (map channel->sexp channels)
+ '()))
+ (configuration-file #+config-file))))
+
+(define (provenance-entry config-file)
+ "Return system entries describing the operating system provenance: the
+channels in use and CONFIG-FILE, if it is true."
+ (define profile
+ (current-profile))
+
+ (define channels
+ (and=> profile profile-channels))
+
+ (mbegin %store-monad
+ (let ((config-file (cond ((string? config-file)
+ (local-file config-file "configuration.scm"))
+ ((not config-file)
+ #f)
+ (else
+ config-file))))
+ (return `(("provenance" ,(provenance-file channels config-file))
+ ,@(if channels
+ `(("channels.scm"
+ ,(plain-file "channels.scm"
+ (object->pretty-string
+ `(list
+ ,@(map channel->code channels))))))
+ '())
+ ,@(if config-file
+ `(("configuration.scm" ,config-file))
+ '()))))))
+
+(define provenance-service-type
+ (service-type (name 'provenance)
+ (extensions
+ (list (service-extension system-service-type
+ provenance-entry)))
+ (default-value #f) ;the OS config file
+ (description
+ "Store provenance information about the system in the system
+itself: the channels used when building the system, and its configuration
+file, when available.")))
+
+\f
+;;;
+;;; Cleanup.
+;;;
+
(define (cleanup-gexp _)
- "Return as a monadic value a gexp to clean up /tmp and similar places upon
-boot."
- (define %modules
- '((guix build utils)))
-
- (mlet %store-monad ((modules (imported-modules %modules))
- (compiled (compiled-modules %modules)))
- (return #~(begin
- (eval-when (expand load eval)
- ;; Make sure 'use-modules' below succeeds.
- (set! %load-path (cons #$modules %load-path))
- (set! %load-compiled-path
- (cons #$compiled %load-compiled-path)))
-
- (use-modules (guix build utils))
-
- ;; Clean out /tmp and /var/run.
- ;;
- ;; XXX This needs to happen before service activations, so it
- ;; has to be here, but this also implicitly assumes that /tmp
- ;; and /var/run are on the root partition.
- (false-if-exception (delete-file-recursively "/tmp"))
- (false-if-exception (delete-file-recursively "/var/run"))
- (false-if-exception (mkdir "/tmp"))
- (false-if-exception (chmod "/tmp" #o1777))
- (false-if-exception (mkdir "/var/run"))
- (false-if-exception (chmod "/var/run" #o755))))))
+ "Return a gexp to clean up /tmp and similar places upon boot."
+ (with-imported-modules '((guix build utils))
+ #~(begin
+ (use-modules (guix build utils))
+
+ ;; Clean out /tmp and /var/run.
+ ;;
+ ;; XXX This needs to happen before service activations, so it
+ ;; has to be here, but this also implicitly assumes that /tmp
+ ;; and /var/run are on the root partition.
+ (letrec-syntax ((fail-safe (syntax-rules ()
+ ((_ exp rest ...)
+ (begin
+ (catch 'system-error
+ (lambda () exp)
+ (const #f))
+ (fail-safe rest ...)))
+ ((_)
+ #t))))
+ ;; Ignore I/O errors so the system can boot.
+ (fail-safe
+ ;; Remove stale Shadow lock files as they would lead to
+ ;; failures of 'useradd' & co.
+ (delete-file "/etc/group.lock")
+ (delete-file "/etc/passwd.lock")
+ (delete-file "/etc/.pwd.lock") ;from 'lckpwdf'
+
+ ;; Force file names to be decoded as UTF-8. See
+ ;; <https://bugs.gnu.org/26353>.
+ (setenv "GUIX_LOCPATH"
+ #+(file-append glibc-utf8-locales "/lib/locale"))
+ (setlocale LC_CTYPE "en_US.utf8")
+ (delete-file-recursively "/tmp")
+ (delete-file-recursively "/var/run")
+
+ (mkdir "/tmp")
+ (chmod "/tmp" #o1777)
+ (mkdir "/var/run")
+ (chmod "/var/run" #o755)
+ (delete-file-recursively "/run/udev/watch.old"))))))
(define cleanup-service-type
;; Service that cleans things up in /tmp and similar.
(service-type (name 'cleanup)
(extensions
(list (service-extension boot-service-type
- cleanup-gexp)))))
-
-(define* (file-union name files) ;FIXME: Factorize.
- "Return a <computed-file> that builds a directory containing all of FILES.
-Each item in FILES must be a list where the first element is the file name to
-use in the new directory, and the second element is a gexp denoting the target
-file."
- (computed-file name
- #~(begin
- (mkdir #$output)
- (chdir #$output)
- #$@(map (match-lambda
- ((target source)
- #~(symlink #$source #$target)))
- files))))
-
-(define (directory-union name things)
- "Return a directory that is the union of THINGS."
- (match things
- ((one)
- ;; Only one thing; return it.
- one)
- (_
- (computed-file name
- #~(begin
- (use-modules (guix build union))
- (union-build #$output '#$things))
- #:modules '((guix build union))))))
+ cleanup-gexp)))
+ (description
+ "Delete files from @file{/tmp}, @file{/var/run}, and other
+temporary locations at boot time.")))
(define* (activation-service->script service)
"Return as a monadic value the activation script for SERVICE, a service of
ACTIVATION-SCRIPT-TYPE."
- (activation-script (service-parameters service)))
+ (activation-script (service-value service)))
(define (activation-script gexps)
"Return the system's activation script, which evaluates GEXPS."
- (define %modules
- '((gnu build activation)
- (gnu build linux-boot)
- (gnu build linux-modules)
- (gnu build file-systems)
- (guix build utils)
- (guix build syscalls)
- (guix elf)))
-
- (define (service-activations)
- ;; Return the activation scripts for SERVICES.
- (mapm %store-monad
- (cut gexp->file "activate-service" <>)
- gexps))
-
- (mlet* %store-monad ((actions (service-activations))
- (modules (imported-modules %modules))
- (compiled (compiled-modules %modules)))
- (gexp->file "activate"
- #~(begin
- (eval-when (expand load eval)
- ;; Make sure 'use-modules' below succeeds.
- (set! %load-path (cons #$modules %load-path))
- (set! %load-compiled-path
- (cons #$compiled %load-compiled-path)))
-
- (use-modules (gnu build activation))
-
- ;; Make sure /bin/sh is valid and current.
- (activate-/bin/sh
- (string-append #$(canonical-package bash) "/bin/sh"))
-
- ;; Run the services' activation snippets.
- ;; TODO: Use 'load-compiled'.
- (for-each primitive-load '#$actions)
-
- ;; Set up /run/current-system.
- (activate-current-system)))))
+ (define actions
+ (map (cut program-file "activate-service.scm" <>) gexps))
+
+ (program-file "activate.scm"
+ (with-imported-modules (source-module-closure
+ '((gnu build activation)
+ (guix build utils)))
+ #~(begin
+ (use-modules (gnu build activation)
+ (guix build utils))
+
+ ;; Make sure the user accounting database exists. If it
+ ;; does not exist, 'setutxent' does not create it and
+ ;; thus there is no accounting at all.
+ (close-port (open-file "/var/run/utmpx" "a0"))
+
+ ;; Same for 'wtmp', which is populated by mingetty et
+ ;; al.
+ (mkdir-p "/var/log")
+ (close-port (open-file "/var/log/wtmp" "a0"))
+
+ ;; Set up /run/current-system. Among other things this
+ ;; sets up locales, which the activation snippets
+ ;; executed below may expect.
+ (activate-current-system)
+
+ ;; Run the services' activation snippets.
+ ;; TODO: Use 'load-compiled'.
+ (for-each primitive-load '#$actions)))))
(define (gexps->activation-gexp gexps)
"Return a gexp that runs the activation script containing GEXPS."
- (mlet %store-monad ((script (activation-script gexps)))
- (return #~(primitive-load #$script))))
+ #~(primitive-load #$(activation-script gexps)))
(define (second-argument a b) b)
(extensions
(list (service-extension boot-service-type
gexps->activation-gexp)))
- (compose append)
- (extend second-argument)))
+ (compose identity)
+ (extend second-argument)
+ (description
+ "Run @dfn{activation} code at boot time and upon
+@command{guix system reconfigure} completion.")))
(define %activation-service
;; The activation service produces the activation script from the gexps it
;; Let users debug their own processes!
(activate-ptrace-attach)))
-(define linux-bare-metal-service-type
- (service-type (name 'linux-bare-metal)
- (extensions
- (list (service-extension activation-service-type
- (const %linux-kernel-activation))))))
-
(define %linux-bare-metal-service
;; The service that does things that are needed on the "bare metal", but not
;; necessary or impossible in a container.
- (service linux-bare-metal-service-type #f))
+ (simple-service 'linux-bare-metal
+ activation-service-type
+ %linux-kernel-activation))
+
+
+(define special-files-service-type
+ ;; Service to install "special files" such as /bin/sh and /usr/bin/env.
+ (service-type
+ (name 'special-files)
+ (extensions
+ (list (service-extension activation-service-type
+ (lambda (files)
+ #~(activate-special-files '#$files)))))
+ (compose concatenate)
+ (extend append)
+ (description
+ "Add special files to the root file system---e.g.,
+@file{/usr/bin/env}.")))
+
+(define (extra-special-file file target)
+ "Use TARGET as the \"special file\" FILE. For example, TARGET might be
+ (file-append coreutils \"/bin/env\")
+and FILE could be \"/usr/bin/env\"."
+ (simple-service (string->symbol (string-append "special-file-" file))
+ special-files-service-type
+ `((,file ,target))))
(define (etc-directory service)
"Return the directory for SERVICE, a service of type ETC-SERVICE-TYPE."
- (files->etc-directory (service-parameters service)))
+ (files->etc-directory (service-value service)))
(define (files->etc-directory files)
(file-union "etc" files))
#~(activate-etc #$etc))))
(service-extension system-service-type etc-entry)))
(compose concatenate)
- (extend append)))
+ (extend append)
+ (description "Populate the @file{/etc} directory.")))
(define (etc-service files)
"Return a new service of ETC-SERVICE-TYPE that populates /etc with FILES.
#~(activate-setuid-programs
(list #$@programs))))))
(compose concatenate)
- (extend append)))
+ (extend append)
+ (description
+ "Populate @file{/run/setuid-programs} with the specified
+executables, making them setuid-root.")))
(define (packages->profile-entry packages)
"Return a system entry for the profile containing PACKAGES."
(mlet %store-monad ((profile (profile-derivation
- (manifest (map package->manifest-entry
- (delete-duplicates packages eq?))))))
+ (packages->manifest
+ (delete-duplicates packages eq?)))))
(return `(("profile" ,profile)))))
(define profile-service-type
(list (service-extension system-service-type
packages->profile-entry)))
(compose concatenate)
- (extend append)))
+ (extend append)
+ (description
+ "This is the @dfn{system profile}, available as
+@file{/run/current-system/profile}. It contains packages that the sysadmin
+wants to be globally available to all the system users.")))
(define (firmware->activation-gexp firmware)
"Return a gexp to make the packages listed in FIRMWARE loadable by the
(list (service-extension activation-service-type
firmware->activation-gexp)))
(compose concatenate)
- (extend append)))
+ (extend append)
+ (description
+ "Make ``firmware'' files loadable by the operating system
+kernel. Firmware may then be uploaded to some of the machine's devices, such
+as Wifi cards.")))
+
+(define (gc-roots->system-entry roots)
+ "Return an entry in the system's output containing symlinks to ROOTS."
+ (mlet %store-monad ((entry (gexp->derivation
+ "gc-roots"
+ #~(let ((roots '#$roots))
+ (mkdir #$output)
+ (chdir #$output)
+ (for-each symlink
+ roots
+ (map number->string
+ (iota (length roots))))))))
+ (return (if (null? roots)
+ '()
+ `(("gc-roots" ,entry))))))
+
+(define gc-root-service-type
+ ;; A service to associate extra garbage-collector roots to the system. This
+ ;; is a simple hack that guarantees that the system retains references to
+ ;; the given list of roots. Roots must be "lowerable" objects like
+ ;; packages, or derivations.
+ (service-type (name 'gc-roots)
+ (extensions
+ (list (service-extension system-service-type
+ gc-roots->system-entry)))
+ (compose concatenate)
+ (extend append)
+ (description
+ "Register garbage-collector roots---i.e., store items that
+will not be reclaimed by the garbage collector.")
+ (default-value '())))
\f
;;;
;;; Service folding.
;;;
-(define-condition-type &service-error &error
- service-error?)
-
(define-condition-type &missing-target-service-error &service-error
missing-target-service-error?
(service missing-target-service-error-service)
(service ambiguous-target-service-error-service)
(target-type ambiguous-target-service-error-target-type))
+(define (missing-target-error service target-type)
+ (raise
+ (condition (&missing-target-service-error
+ (service service)
+ (target-type target-type))
+ (&message
+ (message
+ (format #f (G_ "no target of type '~a' for service '~a'")
+ (service-type-name target-type)
+ (service-type-name
+ (service-kind service))))))))
+
(define (service-back-edges services)
"Return a procedure that, when passed a <service>, returns the list of
<service> objects that depend on it."
((target)
(vhash-consq target service edges))
(()
- (raise
- (condition (&missing-target-service-error
- (service service)
- (target-type target-type))
- (&message
- (message
- (format #f (_ "no target of type '~a' for service ~s")
- (service-type-name target-type)
- service))))))
+ (missing-target-error service target-type))
(x
(raise
(condition (&ambiguous-target-service-error
(&message
(message
(format #f
- (_ "more than one target service of type '~a'")
+ (G_ "more than one target service of type '~a'")
(service-type-name target-type))))))))))
(fold add-edge edges (service-type-extensions (service-kind service))))
(lambda (node)
(reverse (vhash-foldq* cons '() node edges)))))
+(define (instantiate-missing-services services)
+ "Return SERVICES, a list, augmented with any services targeted by extensions
+and missing from SERVICES. Only service types with a default value can be
+instantiated; other missing services lead to a
+'&missing-target-service-error'."
+ (define (adjust-service-list svc result instances)
+ (fold2 (lambda (extension result instances)
+ (define target-type
+ (service-extension-target extension))
+
+ (match (vhash-assq target-type instances)
+ (#f
+ (let ((default (service-type-default-value target-type)))
+ (if (eq? &no-default-value default)
+ (missing-target-error svc target-type)
+ (let ((new (service target-type)))
+ (values (cons new result)
+ (vhash-consq target-type new instances))))))
+ (_
+ (values result instances))))
+ result
+ instances
+ (service-type-extensions (service-kind svc))))
+
+ (let loop ((services services))
+ (define instances
+ (fold (lambda (service result)
+ (vhash-consq (service-kind service) service
+ result))
+ vlist-null services))
+
+ (define adjusted
+ (fold2 adjust-service-list
+ services instances
+ services))
+
+ ;; If we instantiated services, they might in turn depend on missing
+ ;; services. Loop until we've reached fixed point.
+ (if (= (length adjusted) (vlist-length instances))
+ adjusted
+ (loop adjusted))))
+
(define* (fold-services services
#:key (target-type system-service-type))
"Fold SERVICES by propagating their extensions down to the root of type
(match (find (matching-extension target)
(service-type-extensions (service-kind service)))
(($ <service-extension> _ compute)
- (compute (service-parameters service))))))
+ (compute (service-value service))))))
(match (filter (lambda (service)
(eq? (service-kind service) target-type))
services)
((sink)
- (let loop ((sink sink))
- (let* ((dependents (map loop (dependents sink)))
- (extensions (map (apply-extension sink) dependents))
- (extend (service-type-extend (service-kind sink)))
- (compose (service-type-compose (service-kind sink)))
- (params (service-parameters sink)))
- ;; We distinguish COMPOSE and EXTEND because PARAMS typically has a
- ;; different type than the elements of EXTENSIONS.
- (if extend
- (service (service-kind sink)
- (extend params (compose extensions)))
- sink))))
+ ;; Use the state monad to keep track of already-visited services in the
+ ;; graph and to memoize their value once folded.
+ (run-with-state
+ (let loop ((sink sink))
+ (mlet %state-monad ((visited (current-state)))
+ (match (vhash-assq sink visited)
+ (#f
+ (mlet* %state-monad
+ ((dependents (mapm %state-monad loop (dependents sink)))
+ (visited (current-state))
+ (extensions -> (map (apply-extension sink) dependents))
+ (extend -> (service-type-extend (service-kind sink)))
+ (compose -> (service-type-compose (service-kind sink)))
+ (params -> (service-value sink))
+ (service
+ ->
+ ;; Distinguish COMPOSE and EXTEND because PARAMS typically
+ ;; has a different type than the elements of EXTENSIONS.
+ (if extend
+ (service (service-kind sink)
+ (extend params (compose extensions)))
+ sink)))
+ (mbegin %state-monad
+ (set-current-state (vhash-consq sink service visited))
+ (return service))))
+ ((_ . service) ;SINK was already visited
+ (return service)))))
+ vlist-null))
(()
(raise
(condition (&missing-target-service-error
(service #f)
(target-type target-type))
(&message
- (message (format #f (_ "service of type '~a' not found")
+ (message (format #f (G_ "service of type '~a' not found")
(service-type-name target-type)))))))
(x
(raise
(&message
(message
(format #f
- (_ "more than one target service of type '~a'")
+ (G_ "more than one target service of type '~a'")
(service-type-name target-type)))))))))
;;; services.scm ends here.