[NS D04] Implement a simple speed comparison between scores.
This is not used yet to avoid making the change too big to review,
but D05 will use this. Refer to D05 for how this is going to be
used.
Test: ConnectivityServiceTest
Change-Id: I32c12702c8bce959682b02f157946d3f37b12a0c
diff --git a/core/java/android/net/NetworkScore.java b/core/java/android/net/NetworkScore.java
index d2e59eb..d207e79 100644
--- a/core/java/android/net/NetworkScore.java
+++ b/core/java/android/net/NetworkScore.java
@@ -83,6 +83,65 @@
uplinkBandwidthKBps = uplinkBandwidth;
}
+ /**
+ * Evaluate whether a metrics codes for faster network is faster than another.
+ *
+ * This is a simple comparison of expected speeds. If either of the tested attributes
+ * are unknown, this returns zero. This implementation just assumes downlink bandwidth
+ * is more important than uplink bandwidth, which is more important than latency. This
+ * is not a very good way of evaluating network speed, but it's a start.
+ * TODO : do something more representative of how fast the network feels
+ *
+ * @param other the Metrics to evaluate against
+ * @return a negative integer, zero, or a positive integer as this metrics is worse than,
+ * equally good as (or unknown), or better than the passed Metrics.
+ * @see #compareToPreferringKnown(Metrics)
+ * @hide
+ */
+ // Can't implement Comparable<Metrics> because this is @hide.
+ public int compareTo(@NonNull final Metrics other) {
+ if (downlinkBandwidthKBps != BANDWIDTH_UNKNOWN
+ && other.downlinkBandwidthKBps != BANDWIDTH_UNKNOWN) {
+ if (downlinkBandwidthKBps > other.downlinkBandwidthKBps) return 1;
+ if (downlinkBandwidthKBps < other.downlinkBandwidthKBps) return -1;
+ }
+ if (uplinkBandwidthKBps != BANDWIDTH_UNKNOWN
+ && other.uplinkBandwidthKBps != BANDWIDTH_UNKNOWN) {
+ if (uplinkBandwidthKBps > other.uplinkBandwidthKBps) return 1;
+ if (uplinkBandwidthKBps < other.uplinkBandwidthKBps) return -1;
+ }
+ if (latencyMs != LATENCY_UNKNOWN && other.latencyMs != LATENCY_UNKNOWN) {
+ // Latency : lower is better
+ if (latencyMs > other.latencyMs) return -1;
+ if (latencyMs < other.latencyMs) return 1;
+ }
+ return 0;
+ }
+
+ /**
+ * Evaluate whether a metrics codes for faster network is faster than another.
+ *
+ * This is a simple comparison of expected speeds. If either of the tested attributes
+ * are unknown, this prefers the known attributes. This implementation just assumes
+ * downlink bandwidth is more important than uplink bandwidth, which is more important than
+ * latency. This is not a very good way of evaluating network speed, but it's a start.
+ * TODO : do something more representative of how fast the network feels
+ *
+ * @param other the Metrics to evaluate against
+ * @return a negative integer, zero, or a positive integer as this metrics is worse than,
+ * equally good as (or unknown), or better than the passed Metrics.
+ * @see #compareTo(Metrics)
+ * @hide
+ */
+ public int compareToPreferringKnown(@NonNull final Metrics other) {
+ if (downlinkBandwidthKBps > other.downlinkBandwidthKBps) return 1;
+ if (downlinkBandwidthKBps < other.downlinkBandwidthKBps) return -1;
+ if (uplinkBandwidthKBps > other.uplinkBandwidthKBps) return 1;
+ if (uplinkBandwidthKBps < other.uplinkBandwidthKBps) return -1;
+ // Latency : lower is better
+ return -Integer.compare(latencyMs, other.latencyMs);
+ }
+
/** toString */
public String toString() {
return "latency = " + latencyMs + " downlinkBandwidth = " + downlinkBandwidthKBps
@@ -346,6 +405,33 @@
return mLegacyScore;
}
+ /**
+ * Use the metrics to evaluate whether a network is faster than another.
+ *
+ * This is purely based on the metrics, and explicitly ignores policy or exiting. It's
+ * provided to get a decision on two networks when policy can not decide, or to evaluate
+ * how a network is expected to compare to another if it should validate.
+ *
+ * @param other the score to evaluate against
+ * @return whether this network is probably faster than the other
+ * @hide
+ */
+ public boolean probablyFasterThan(@NonNull final NetworkScore other) {
+ if (mLegacyScore > other.mLegacyScore) return true;
+ final int atEndToEnd = mEndToEndMetrics.compareTo(other.mEndToEndMetrics);
+ if (atEndToEnd > 0) return true;
+ if (atEndToEnd < 0) return false;
+ final int atLinkLayer = mLinkLayerMetrics.compareTo(other.mLinkLayerMetrics);
+ if (atLinkLayer > 0) return true;
+ if (atLinkLayer < 0) return false;
+ final int atEndToEndPreferringKnown =
+ mEndToEndMetrics.compareToPreferringKnown(other.mEndToEndMetrics);
+ if (atEndToEndPreferringKnown > 0) return true;
+ if (atEndToEndPreferringKnown < 0) return false;
+ // If this returns 0, neither is "probably faster" so just return false.
+ return mLinkLayerMetrics.compareToPreferringKnown(other.mLinkLayerMetrics) > 0;
+ }
+
/** Builder for NetworkScore. */
public static class Builder {
private int mPolicy = 0;
