Efforts to make ucloud a python package

ucloud/scheduler/helper.py

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+from collections import Counter
+from functools import reduce
+
+import bitmath
+
+from ucloud.common.host import HostStatus
+from ucloud.common.request import RequestEntry, RequestType
+from ucloud.common.vm import VMStatus
+from ucloud.config import vm_pool, host_pool, request_pool, env_vars
+
+
+def accumulated_specs(vms_specs):
+    if not vms_specs:
+        return {}
+    return reduce((lambda x, y: Counter(x) + Counter(y)), vms_specs)
+
+
+def remaining_resources(host_specs, vms_specs):
+    # Return remaining resources host_specs - vms
+
+    _vms_specs = Counter(vms_specs)
+    _remaining = Counter(host_specs)
+
+    for component in _vms_specs:
+        if isinstance(_vms_specs[component], str):
+            _vms_specs[component] = int(bitmath.parse_string_unsafe(_vms_specs[component]).to_MB())
+        elif isinstance(_vms_specs[component], list):
+            _vms_specs[component] = map(lambda x: int(bitmath.parse_string_unsafe(x).to_MB()), _vms_specs[component])
+            _vms_specs[component] = reduce(lambda x, y: x + y, _vms_specs[component], 0)
+
+    for component in _remaining:
+        if isinstance(_remaining[component], str):
+            _remaining[component] = int(bitmath.parse_string_unsafe(_remaining[component]).to_MB())
+        elif isinstance(_remaining[component], list):
+            _remaining[component] = map(lambda x: int(bitmath.parse_string_unsafe(x).to_MB()), _remaining[component])
+            _remaining[component] = reduce(lambda x, y: x + y, _remaining[component], 0)
+
+    _remaining.subtract(_vms_specs)
+
+    return _remaining
+
+
+class NoSuitableHostFound(Exception):
+    """Exception when no host found that can host a VM."""
+
+
+def get_suitable_host(vm_specs, hosts=None):
+    if hosts is None:
+        hosts = host_pool.by_status(HostStatus.alive)
+
+    for host in hosts:
+        # Filter them by host_name
+        vms = vm_pool.by_host(host.key)
+
+        # Filter them by status
+        vms = vm_pool.by_status(VMStatus.running, vms)
+
+        running_vms_specs = [vm.specs for vm in vms]
+
+        # Accumulate all of their combined specs
+        running_vms_accumulated_specs = accumulated_specs(running_vms_specs)
+
+        # Find out remaining resources after
+        # host_specs - already running vm_specs
+        remaining = remaining_resources(host.specs, running_vms_accumulated_specs)
+
+        # Find out remaining - new_vm_specs
+        remaining = remaining_resources(remaining, vm_specs)
+
+        if all(map(lambda x: x >= 0, remaining.values())):
+            return host.key
+
+    raise NoSuitableHostFound
+
+
+def dead_host_detection():
+    # Bring out your dead! - Monty Python and the Holy Grail
+    hosts = host_pool.by_status(HostStatus.alive)
+    dead_hosts_keys = []
+
+    for host in hosts:
+        # Only check those who claims to be alive
+        if host.status == HostStatus.alive:
+            if not host.is_alive():
+                dead_hosts_keys.append(host.key)
+
+    return dead_hosts_keys
+
+
+def dead_host_mitigation(dead_hosts_keys):
+    for host_key in dead_hosts_keys:
+        host = host_pool.get(host_key)
+        host.declare_dead()
+
+        vms_hosted_on_dead_host = vm_pool.by_host(host_key)
+        for vm in vms_hosted_on_dead_host:
+            vm.declare_killed()
+            vm_pool.put(vm)
+        host_pool.put(host)
+
+
+def assign_host(vm):
+    vm.hostname = get_suitable_host(vm.specs)
+    vm_pool.put(vm)
+
+    r = RequestEntry.from_scratch(type=RequestType.StartVM,
+                                  uuid=vm.uuid,
+                                  hostname=vm.hostname,
+                                  request_prefix=env_vars.get("REQUEST_PREFIX"))
+    request_pool.put(r)
+
+    vm.log.append("VM scheduled for starting")
+    return vm.hostname