the first commit

backend_cache.py

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+# Copyright 2019 Novartis Institutes for BioMedical Research Inc. Licensed
+# under the Apache License, Version 2.0 (the "License"); you may not use
+# this file except in compliance with the License. You may obtain a copy
+# of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless
+# required by applicable law or agreed to in writing, software distributed
+# under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
+# OR CONDITIONS OF ANY KIND, either express or implied. See the License for
+# the specific language governing permissions and limitations under the License.
+
+import time
+from threading import Thread
+
+from flask_api import status
+
+import env
+from cache_entry import CacheEntry
+from cellxgene_exception import CellxgeneException
+from subprocess_backend import SubprocessBackend
+
+process_backend = SubprocessBackend()
+
+
+class BackendCache:
+    def __init__(self):
+        self.entry_list = []
+
+    def get_ports(self):
+        contents = self.entry_list
+        return [c.port for c in contents]
+
+    def check_entry(self, dataset):
+        contents = self.entry_list
+        matches = [c for c in contents if c.dataset == dataset]
+
+        if len(matches) == 0:
+            return None
+        elif len(matches) == 1:
+            return matches[0]
+        else:
+            raise CellxgeneException(
+                status.HTTP_500_INTERNAL_SERVER_ERROR,
+                "Found " + str(len(matches)) + " for " + dataset,
+            )
+
+    def create_entry(self, dataset, file_path, scripts):
+        port = 8000
+        existing_ports = self.get_ports()
+        while port in existing_ports:
+            port += 1
+
+        entry = CacheEntry.for_dataset(dataset, file_path, port)
+
+        background_thread = Thread(
+            target=process_backend.launch, args=(env.cellxgene_location, scripts, entry)
+        )
+        background_thread.start()
+
+        self.entry_list.append(entry)
+
+        time.sleep(1)  # Automatic refresh is too fast, needs a second to pause
+
+        return entry