1/*
2Copyright 2016 The Kubernetes Authors.
3
4Licensed under the Apache License, Version 2.0 (the "License");
5you may not use this file except in compliance with the License.
6You may obtain a copy of the License at
7
8    http://www.apache.org/licenses/LICENSE-2.0
9
10Unless required by applicable law or agreed to in writing, software
11distributed under the License is distributed on an "AS IS" BASIS,
12WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13See the License for the specific language governing permissions and
14limitations under the License.
15*/
16
17package images
18
19import (
20	"time"
21
22	"k8s.io/api/core/v1"
23	"k8s.io/apimachinery/pkg/util/wait"
24	runtimeapi "k8s.io/cri-api/pkg/apis/runtime/v1alpha2"
25	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
26)
27
28type pullResult struct {
29	imageRef string
30	err      error
31}
32
33type imagePuller interface {
34	pullImage(kubecontainer.ImageSpec, []v1.Secret, chan<- pullResult, *runtimeapi.PodSandboxConfig)
35}
36
37var _, _ imagePuller = &parallelImagePuller{}, &serialImagePuller{}
38
39type parallelImagePuller struct {
40	imageService kubecontainer.ImageService
41}
42
43func newParallelImagePuller(imageService kubecontainer.ImageService) imagePuller {
44	return &parallelImagePuller{imageService}
45}
46
47func (pip *parallelImagePuller) pullImage(spec kubecontainer.ImageSpec, pullSecrets []v1.Secret, pullChan chan<- pullResult, podSandboxConfig *runtimeapi.PodSandboxConfig) {
48	go func() {
49		imageRef, err := pip.imageService.PullImage(spec, pullSecrets, podSandboxConfig)
50		pullChan <- pullResult{
51			imageRef: imageRef,
52			err:      err,
53		}
54	}()
55}
56
57// Maximum number of image pull requests than can be queued.
58const maxImagePullRequests = 10
59
60type serialImagePuller struct {
61	imageService kubecontainer.ImageService
62	pullRequests chan *imagePullRequest
63}
64
65func newSerialImagePuller(imageService kubecontainer.ImageService) imagePuller {
66	imagePuller := &serialImagePuller{imageService, make(chan *imagePullRequest, maxImagePullRequests)}
67	go wait.Until(imagePuller.processImagePullRequests, time.Second, wait.NeverStop)
68	return imagePuller
69}
70
71type imagePullRequest struct {
72	spec             kubecontainer.ImageSpec
73	pullSecrets      []v1.Secret
74	pullChan         chan<- pullResult
75	podSandboxConfig *runtimeapi.PodSandboxConfig
76}
77
78func (sip *serialImagePuller) pullImage(spec kubecontainer.ImageSpec, pullSecrets []v1.Secret, pullChan chan<- pullResult, podSandboxConfig *runtimeapi.PodSandboxConfig) {
79	sip.pullRequests <- &imagePullRequest{
80		spec:             spec,
81		pullSecrets:      pullSecrets,
82		pullChan:         pullChan,
83		podSandboxConfig: podSandboxConfig,
84	}
85}
86
87func (sip *serialImagePuller) processImagePullRequests() {
88	for pullRequest := range sip.pullRequests {
89		imageRef, err := sip.imageService.PullImage(pullRequest.spec, pullRequest.pullSecrets, pullRequest.podSandboxConfig)
90		pullRequest.pullChan <- pullResult{
91			imageRef: imageRef,
92			err:      err,
93		}
94	}
95}
96