1. configurationprovider介面，提供了getconfiguration()方法，用於獲取不同元件的配置。
2. lifecycleaware介面，提供了三個方法，start() stop()和getlifecyclestate()，分別用於元件的啟動 停止以及元件在生命週期中處的狀態，可以說這個介面貫穿於整個flume中。
public synchronized void start()
}
接下來supervisor再被例項化lifecyclesupervisor物件的時候會做哪些工作呢？
即new lifecyclesupervisor(),建構函式做了什麼
public lifecyclesupervisor()主要初始化了乙個有10個執行緒，上限是20的執行緒池
再回到之前supervise(lifecycleaware lifecycleaware,supervisorpolicy policy, lifecyclestate desiredstate)方法，它是具體執行啟動各個元件的方法
public synchronized void supervise(lifecycleaware lifecycleaware,
supervisorpolicy policy, lifecyclestate desiredstate)
preconditions.checkstate(!supervisedprocesses.containskey(lifecycleaware),
"refusing to supervise " + lifecycleaware + " more than once");
if (logger.isdebugenabled()) policy:{} desiredstate:{}",
new object );
}supervisoree process = new supervisoree();
process.status = new status();
process.policy = policy;
process.status.desiredstate = desiredstate;
process.status.error = false;
monitorrunnable monitorrunnable = new monitorrunnable();
monitorrunnable.lifecycleaware = lifecycleaware;
monitorrunnable.supervisoree = process;
monitorrunnable.monitorservice = monitorservice;
supervisedprocesses.put(lifecycleaware, process);
scheduledfuture<?> future = monitorservice.schedulewithfixeddelay(
monitorrunnable, 0, 3, timeunit.seconds);
monitorfutures.put(lifecycleaware, future);
}
首先會把元件的渴望的狀態desiredstate(如lifecyclestate.start)和策略policy(如new supervisorpolicy.alwaysrestartpolicy())放到靜態內部類supervisoree中，再將元件lifecycleaware及之前的資訊，一併傳值到monitorrunnable執行緒中，下面執行緒類monitorrunnable的run方法會根據switch case匹配的值去執行不同操作，當前回到start流程，執行lifecycleaware.start()，完成元件的啟動
@override
public void run() supervisoree:{}", lifecycleaware,
supervisoree);
long now = system.currenttimemillis();
try ", lifecycleaware);
supervisoree.status.firstseen = now;
}supervisoree.status.lastseen = now;
synchronized (lifecycleaware) ", lifecycleaware);
return;
} else if (supervisoree.status.error) is in error state, and flume will not"
+ "attempt to change its state", lifecycleaware);
return;
}supervisoree.status.lastseenstate = lifecycleaware.getlifecyclestate();
if (!lifecycleaware.getlifecyclestate().equals(
supervisoree.status.desiredstate)) from {} to {} (failures:{})",
new object );
switch (supervisoree.status.desiredstate) catch (throwable e) stopped, since it could not be"
+ "successfully started due to missing dependencies",
lifecycleaware);
} catch (throwable e1) due to missing dependencies."
+ " please shutdown the agent"
+ "or disable this component, or the agent will be"
+ "in an undefined state.", e1);
supervisoree.status.error = true;
if (e1 instanceof error)
// set the state to stop, so that the conf poller can
// proceed.}}
supervisoree.status.failures++;
}break;
case stop:
try catch (throwable e)
supervisoree.status.failures++;
}break;
default:
logger.warn("i refuse to acknowledge {} as a desired state",
supervisoree.status.desiredstate);
}if (!supervisoree.policy.isvalid(lifecycleaware, supervisoree.status)) of {} has been violated - supervisor should exit!",
supervisoree.policy, lifecycleaware);}}
}} catch(throwable t)
logger.debug("status check complete");
}
接下來再呼叫lifecycleaware.start()後，會根據元件的不同，找到對應元件的runner類，這裡以source中的pollablesourcerunner為例，flume source提供了兩種類別的source即:eventdrivensource和pollablesource,eventdrivensource為事件驅動，pollablesource則是輪詢機制，pollablesource型別的啟動依賴於pollablesourcerunner，在pollablesourcerunner內部會有乙個用於輪詢的類
pollingrunner，在執行的過程中會根據pollablesource型別特有的source.process()返回值的狀態，進行sleep
public void run() ", source);
while (!shouldstop.get()) else
} catch (interruptedexception e) catch (eventdeliveryexception e) catch (exception e) catch (interruptedexception ex) }}
logger.debug("polling runner exiting. metrics:{}", countergroup);
}
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