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Pick first: go IDLE if all subchannels go IDLE #1066

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merged 1 commit into from
Oct 4, 2019
+42 −20
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Pick first: go IDLE if all subchannels go IDLE #1066

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62 changes: 42 additions & 20 deletions packages/grpc-js/src/load-balancer-pick-first.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,14 @@ class PickFirstPicker implements Picker {
}
}

interface ConnectivityStateCounts {
[ConnectivityState.CONNECTING]: number,
[ConnectivityState.IDLE]: number,
[ConnectivityState.READY]: number,
[ConnectivityState.SHUTDOWN]: number,
[ConnectivityState.TRANSIENT_FAILURE]: number
}

export class PickFirstLoadBalancer implements LoadBalancer {
/**
* The list of backend addresses most recently passed to `updateAddressList`.
Expand All @@ -75,11 +83,8 @@ export class PickFirstLoadBalancer implements LoadBalancer {
* recently started connection attempt.
*/
private currentSubchannelIndex = 0;
/**
* The number of subchannels in the `subchannels` list currently in the
* CONNECTING state. Used to determine the overall load balancer state.
*/
private subchannelConnectingCount = 0;

private subchannelStateCounts: ConnectivityStateCounts;
/**
* The currently picked subchannel used for making calls. Populated if
* and only if the load balancer's current state is READY. In that case,
Expand Down Expand Up @@ -111,17 +116,20 @@ export class PickFirstLoadBalancer implements LoadBalancer {
*/
constructor(private channelControlHelper: ChannelControlHelper) {
this.updateState(ConnectivityState.IDLE, new QueuePicker(this));
this.subchannelStateCounts = {
[ConnectivityState.CONNECTING]: 0,
[ConnectivityState.IDLE]: 0,
[ConnectivityState.READY]: 0,
[ConnectivityState.SHUTDOWN]: 0,
[ConnectivityState.TRANSIENT_FAILURE]: 0
};
this.subchannelStateListener = (
subchannel: Subchannel,
previousState: ConnectivityState,
newState: ConnectivityState
) => {
if (previousState === ConnectivityState.CONNECTING) {
this.subchannelConnectingCount -= 1;
}
if (newState === ConnectivityState.CONNECTING) {
this.subchannelConnectingCount += 1;
}
this.subchannelStateCounts[previousState] -= 1;
this.subchannelStateCounts[newState] += 1;
/* If the subchannel we most recently attempted to start connecting
* to goes into TRANSIENT_FAILURE, immediately try to start
* connecting to the next one instead of waiting for the connection
Expand All @@ -138,10 +146,14 @@ export class PickFirstLoadBalancer implements LoadBalancer {
} else {
if (this.currentPick === null) {
if (this.triedAllSubchannels) {
const newLBState =
this.subchannelConnectingCount > 0
? ConnectivityState.CONNECTING
: ConnectivityState.TRANSIENT_FAILURE;
let newLBState: ConnectivityState;
if (this.subchannelStateCounts[ConnectivityState.CONNECTING] > 0) {
newLBState = ConnectivityState.CONNECTING;
} else if (this.subchannelStateCounts[ConnectivityState.TRANSIENT_FAILURE] > 0) {
newLBState = ConnectivityState.TRANSIENT_FAILURE;
} else {
newLBState = ConnectivityState.IDLE;
}
if (newLBState !== this.currentState) {
if (newLBState === ConnectivityState.TRANSIENT_FAILURE) {
this.updateState(newLBState, new UnavailablePicker());
Expand Down Expand Up @@ -169,10 +181,14 @@ export class PickFirstLoadBalancer implements LoadBalancer {
this.pickedSubchannelStateListener
);
if (this.subchannels.length > 0) {
const newLBState =
this.subchannelConnectingCount > 0
? ConnectivityState.CONNECTING
: ConnectivityState.TRANSIENT_FAILURE;
let newLBState: ConnectivityState;
if (this.subchannelStateCounts[ConnectivityState.CONNECTING] > 0) {
newLBState = ConnectivityState.CONNECTING;
} else if (this.subchannelStateCounts[ConnectivityState.TRANSIENT_FAILURE] > 0) {
newLBState = ConnectivityState.TRANSIENT_FAILURE;
} else {
newLBState = ConnectivityState.IDLE;
}
if (newLBState === ConnectivityState.TRANSIENT_FAILURE) {
this.updateState(newLBState, new UnavailablePicker());
} else {
Expand Down Expand Up @@ -253,7 +269,13 @@ export class PickFirstLoadBalancer implements LoadBalancer {
subchannel.unref();
}
this.currentSubchannelIndex = 0;
this.subchannelConnectingCount = 0;
this.subchannelStateCounts = {
[ConnectivityState.CONNECTING]: 0,
[ConnectivityState.IDLE]: 0,
[ConnectivityState.READY]: 0,
[ConnectivityState.SHUTDOWN]: 0,
[ConnectivityState.TRANSIENT_FAILURE]: 0
};
this.subchannels = [];
this.triedAllSubchannels = false;
}
Expand Down