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Fix config being loaded twice #293

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Merged
merged 5 commits into from
Mar 27, 2021
Merged

Fix config being loaded twice #293

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38c8d9f
:sparkles: create memoizing AgentConfigSupplier encapsulating double-…
ryandens Mar 21, 2021
49bd84b
:recycle: refactor HypertraceConfig to use thread-safe AgentConfigSup…
ryandens Mar 21, 2021
ca8f431
Revert ":recycle: refactor HypertraceConfig to use thread-safe AgentC…
ryandens Mar 27, 2021
da325bd
:ok_hand: move double-checked locking implementation back into Hypert…
ryandens Mar 27, 2021
db27d36
:fire: delete AgentConfigSupplier as it is now unused
ryandens Mar 27, 2021
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7 changes: 5 additions & 2 deletions javaagent-core/src/main/java/org/hypertrace/agent/core/config/HypertraceConfig.java
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,8 @@ private HypertraceConfig() {}
// so avoiding for perf reasons
private static volatile boolean servletCausingException;

private static AgentConfig agentConfig;
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Thanks for putting this together. I like the testability, but on the other hand, I would like to keep it as simple as possible. Would it be enough to just use volatile on this property and not use the supplier approach?

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Yeah, no problem! I think in addition to making this field volatile, we would also want to synchronize the write to this field in HypertraceConfig.reset() unless you're not worried about this class being thread-safe when APIs exposed for testing purpose are in use.

// volatile field in order to properly handle lazy initialization with double-checked locking
private static volatile AgentConfig agentConfig;

static final String DEFAULT_SERVICE_NAME = "unknown";
static final String DEFAULT_REPORTING_ENDPOINT = "http://localhost:9411/api/v2/spans";
Expand Down Expand Up @@ -123,7 +124,9 @@ private static boolean isHypertraceType(String message) {
/** Reset the config, use only in tests. */
@VisibleForTesting
public static void reset() {
agentConfig = null;
synchronized (HypertraceConfig.class) {
agentConfig = null;
}
}

private static AgentConfig load() throws IOException {
Expand Down