gnocchi-采样数据存储流程分析(001)--数据存储

1 数据存储

 

1.1 增加一条采样数据

gnocchi --debug measures add -m 2016-04-16T14:33:[email protected] --resource-id 3068f5ec-0d37-419a-929d-0505efaf908c vm_meteric_001  

1.2 Rest api处理接口

源代码位于： gnocchi/rest/__init__.py中NamedMetricController：

在lookup接口中，根据传入的meter的name以及resource，在索引数据库中查找到对应的metric信息,并返回该metric的数据处理方式

 

class NamedMetricController(rest.RestController):
    def __init__(self, resource_id, resource_type):
        self.resource_id = resource_id
        self.resource_type = resource_type

    @pecan.expose()
    def _lookup(self, name, *remainder):
        details = True ifpecan.request.method == 'GET'else False
        m = pecan.request.indexer.list_metrics(details=details,
                                               name=name,
                                               resource_id=self.resource_id)
        if m:
            return MetricController(m[0]), remainder

        resource = pecan.request.indexer.get_resource(self.resource_type,self.resource_id)
        if resource:
            abort(404, indexer.NoSuchMetric(name))
        else:
            abort(404, indexer.NoSuchResource(self.resource_id))

 

1.3 MetricController增加记录post_measures

源代码位于： gnocchi/rest/__init__.py中MeticController：

根据pecan.request.storage定义的后端存储类型，调用对应的add_measures接口，本文主要以本地存储file进行分析。

 

@pecan.expose()
def post_measures(self):
    self.enforce_metric("post measures")
    params = deserialize()
    if not isinstance(params,list):
        abort(400, "Invalid input for measures")
    if params:
        # gnocchi.storage.file.FileStorage
        pecan.request.storage.add_measures(
            self.metric, six.moves.map(MeasureSchema, params))
    pecan.response.status = 202

 

1.4 Add_measures

该方法的父类源码位于gnocchi/storage/_carbonara.py的CarbnonaraBaseStorage，其他的存储后端实现add_measures中的_store_measures()方法

def add_measures(self, metric, measures):
    self._store_measures(metric, msgpackutils.dumps(
        list(map(tuple, measures))))

 

1.5 file驱动的_store_measures方法

该源码位于 gnocchi/storage/file.py的FileStorage类中：

def _store_measures(self, metric, data):
    tmpfile = self._get_tempfile()

#临时文件路径为/var/lib/gnocchi/tmp
    tmpfile.write(data)
    tmpfile.close()
    path = self._build_measure_path(metric.id,True)

#该路径为/var/lib/gnocchi/measure/metric.id/+随机uuid+时间戳
    while True:
        try:
            os.rename(tmpfile.name, path)
            break
        except OSErroras e:
            if e.errno != errno.ENOENT:
                raise
            try:
                os.mkdir(self._build_measure_path(metric.id))
            except OSErroras e:
                # NOTE(jd) It's possible that another process created the
                # path just before us! In this case, good for us, let's do
                # nothing then! (see bug #1475684)
                ife.errno != errno.EEXIST:
                    raise

具体如下：