Instrument Caches

Sentry offers a cache-monitoring dashboard that can be auto-instrumented by some SDKs. If you're Go, you can manually instrument your cache operations and use Sentry to monitor your caching performance to get a look into how your caching solution is performing by following the setup instructions below.

To allow Sentry to track cache performance, you'll need to create two spans:

• One for when an item is put into the cache.
• Another for when an item is fetched from the cache.

Ensure there is an active transaction when creating the spans. For more information, see Tracing.

For detailed information about the available data, see the Cache Module developer specification.

Custom Instrumentation

If you're using anything other than an SDK that supports auto-instrumentation, you'll need to manually instrument the Cache Module as described below.

Add Span When Putting Data Into the Cache

For unsupported cache solutions, use custom instrumentation to emit cache spans:

• Set the cache value using your preferred cache library.
• Wrap the part of your application that adds data to the cache in a span.
• Set op to cache.put.
• Optionally, set cache.item_size to the size of the cached item.

Example (Go)

key := "cache_key"
value := "cache_value"

parentSpan := sentry.StartSpan(context.Background(), "parent_span")

if parentSpan != nil {
    span := parentSpan.StartChild("cache.put")
    defer span.Finish()

    // Perform the cache operation
    err := cache.Put(key, value)

    span.SetData("network.peer.address", "127.0.0.1")
    span.SetData("network.peer.port", 9000)
    span.SetData("cache.key", key)
    span.SetData("cache.item_size", len(value))

    if err != nil {
        span.SetTag("error", err.Error())
    }
}

Add Span When Retrieving Data From the Cache

For unsupported cache solutions, use custom instrumentation to emit cache spans:

Fetch the cached value using your preferred cache library. Wrap the part of your application that retrieves data from the cache in a span. Set op to cache.get. Set cache.hit to true or false, depending on whether the value was found. Optionally, set cache.item_size to the size of the retrieved item.

Example:

key := "cache_key"
var value string

parentSpan := sentry.StartSpan(context.Background(), "parent_span")

if parentSpan != nil {
    span := parentSpan.StartChild("cache.get")
    defer span.Finish()

    // Perform the cache operation
    value, err := cache.Get(key)

    span.SetData("network.peer.address", "127.0.0.1")
    span.SetData("network.peer.port", 9000)
    span.SetData("cache.key", key)

    if err == nil && value != "" {
        span.SetData("cache.hit", true)
        span.SetData("cache.item_size", len(value))
    } else {
        span.SetData("cache.hit", false)
    }
}

You should now have the right spans in place. Head over to the Cache dashboard to see how your cache is performing.