Add jenkinsfile (#415)

* chore: add jenkins file

* chore: remove cuda_arch

* chore: replace Float.parsefloat with string check

* chore: add pip mirror

* chore: fix add MMCV_WITH_OPS env var

* chore: fix undefined symbol _Z16THPVariable_WrapN2at6TensorE

* chore: add comment

* chore: fix multi docker running under same dir error

* chore: rm dir after build

* chore: fix rm

* chore: also rm tmp dir

* chore: use sensetime docker

* feat: use torch-pre-installed docker

* fix: fix index error

Jenkinsfile

+def docker_images = ["registry.cn-hangzhou.aliyuncs.com/sensetime/openmmlab:cuda10.1-cudnn7-devel-ubuntu18.04-py37-pt1.3",
+                     "registry.cn-hangzhou.aliyuncs.com/sensetime/openmmlab:cuda10.2-cudnn7-devel-ubuntu18.04-py37-pt1.5"]
+def torch_versions = ["1.3.0", "1.5.0"]
+def torchvision_versions = ["0.4.2", "0.6.0"]
+
+
+def get_stages(docker_image, folder) {
+    def pip_mirror = "-i http://mirrors.aliyun.com/pypi/simple --trusted-host mirrors.aliyun.com"
+    stages = {
+        docker.image(docker_image).inside('-u root --gpus all --net host') {
+            sh "cp -r ${env.WORKSPACE} ${env.WORKSPACE}-${folder}"
+            try {
+                dir("${env.WORKSPACE}-${folder}") {
+                    stage("before_install") {
+                        sh "apt-get update && apt-get install -y ninja-build"
+                    }
+                    stage("dependencies") {
+                        // torch and torchvision are pre-installed in dockers
+                        sh "pip list | grep torch"
+                        sh "apt-get install -y ffmpeg libturbojpeg"
+                        sh "pip install pytest coverage lmdb PyTurboJPEG ${pip_mirror}"
+                    }
+                    stage("build") {
+                        sh "MMCV_WITH_OPS=1 pip install -e . ${pip_mirror}"
+                    }
+                    stage("test") {
+                        sh "coverage run --branch --source=mmcv -m pytest tests/"
+                        sh "coverage xml"
+                        sh "coverage report -m"
+                    }
+                }
+            } finally {
+                sh "rm -rf ${env.WORKSPACE}-${folder} ${env.WORKSPACE}-${folder}@tmp"
+            }
+        }
+    }
+    return stages
+}
+
+
+node('master') {
+    // fetch latest change from SCM (Source Control Management)
+    checkout scm
+
+    def stages = [:]
+    for (int i = 0; i < docker_images.size(); i++) {
+        def docker_image = docker_images[i]
+        def torch = torch_versions[i]
+        def torchvision = torchvision_versions[i]
+        def tag = docker_image + '_' + torch + '_' + torchvision
+        def folder = "${i}"
+        stages[tag] = get_stages(docker_image, folder)
+    }
+    parallel stages
+}