Freshness TTL Should be Able to be Disabled in Favor of Using ETag Alone to Determine Whether URL Metric is Stale

Oct 13, 2025 by wbrum.org 61 views

Freshness TTL Should be Able to be Disabled in Favor of Using ETag Alone to Determine Whether URL Metric is Stale

Introduction

In the world of web performance optimization, freshness TTL (time to live) plays a crucial role in determining whether a URL metric is stale or not. However, with the introduction of ETags (entity tags) in WordPress performance, it has become possible to consider ETags as a factor in determining the freshness of a URL metric. In this article, we will explore the possibility of disabling freshness TTL in favor of using ETags alone to determine whether a URL metric is stale.

Background

The concept of freshness TTL was introduced in WordPress performance to ensure that URL metrics are updated regularly and do not become stale. However, with the introduction of ETags, it has become possible to consider ETags as a factor in determining the freshness of a URL metric. ETags are unique identifiers that are generated for each resource on a website, and they can be used to determine whether a resource has changed or not.

The Current Implementation

Currently, the freshness TTL is used to determine whether a URL metric is stale or not. The freshness TTL is a positive integer that represents the number of seconds after which a URL metric is considered stale. However, with the introduction of ETags, it has become possible to consider ETags as a factor in determining the freshness of a URL metric.

The Problem

The problem with the current implementation is that it does not allow the freshness TTL to be disabled in favor of using ETags alone to determine whether a URL metric is stale. This is because the constructor of the OD_URL_Metric_Group class requires a positive integer for the freshness TTL, and setting it to -1 would fail.

The Solution

To solve this problem, we need to modify the OD_URL_Metric_Group class to allow the freshness TTL to be disabled in favor of using ETags alone to determine whether a URL metric is stale. This can be achieved by introducing a new filter od_url_metric_freshness_ttl that allows the freshness TTL to be set to -1.

The Filter

The filter od_url_metric_freshness_ttl can be used to set the freshness TTL to -1, which would disable the freshness TTL and use ETags alone to determine whether a URL metric is stale. This can be achieved by adding the following code to the functions.php file:

add_filter( 'od_url_metric_freshness_ttl', function () { return -1; } );

The Benefits

Allowing the freshness TTL to be disabled in favor of using ETags alone to determine whether a URL metric is stale has several benefits. Firstly, it would allow URL metrics to remain fresh indefinitely as long as the ETags do not change, that is, if the state of the site does not change. Secondly, it would reduce the number of requests made to the server to update the URL metrics, which would improve the performance of the website.

Conclusion

In conclusion, allowing the freshness TTL to be disabled in favor of using ETags alone to determine whether a URL metric is stale is a beneficial feature that would improve the performance of the website. By introducing a new filter od_url_metric_freshness_ttl that allows the freshness TTL to be set to -1, we can achieve this feature and improve the performance of the website.

Future Work

Future work on this feature would involve modifying the OD_URL_Metric_Group class to allow the freshness TTL to be disabled in favor of using ETags alone to determine whether a URL metric is stale. This would involve introducing a new filter od_url_metric_freshness_ttl that allows the freshness TTL to be set to -1, and modifying the OD_URL_Metric_Group class to use ETags alone to determine whether a URL metric is stale.

Code Changes

The following code changes would be required to implement this feature:

Modify the OD_URL_Metric_Group class to allow the freshness TTL to be set to -1.
Introduce a new filter od_url_metric_freshness_ttl that allows the freshness TTL to be set to -1.
Modify the OD_URL_Metric_Group class to use ETags alone to determine whether a URL metric is stale.

Commit Message

The commit message for this feature would be:

Allow freshness TTL to be disabled in favor of using ETags alone to determine whether a URL metric is stale.

API Documentation

The API documentation for this feature would include the following information:

The od_url_metric_freshness_ttl filter allows the freshness TTL to be set to -1, which would disable the freshness TTL and use ETags alone to determine whether a URL metric is stale.
The OD_URL_Metric_Group class has been modified to allow the freshness TTL to be set to -1.
The OD_URL_Metric_Group class uses ETags alone to determine whether a URL metric is stale when the freshness TTL is set to -1.
Freshness TTL Should be Able to be Disabled in Favor of Using ETag Alone to Determine Whether URL Metric is Stale: Q&A

Introduction

In our previous article, we discussed the possibility of disabling freshness TTL in favor of using ETags alone to determine whether a URL metric is stale. In this article, we will answer some frequently asked questions about this feature.

Q: What is freshness TTL?

A: Freshness TTL (time to live) is a mechanism that determines whether a URL metric is stale or not. It is a positive integer that represents the number of seconds after which a URL metric is considered stale.

Q: Why do we need to disable freshness TTL?

A: With the introduction of ETags (entity tags) in WordPress performance, it has become possible to consider ETags as a factor in determining the freshness of a URL metric. Disabling freshness TTL would allow URL metrics to remain fresh indefinitely as long as the ETags do not change, that is, if the state of the site does not change.

Q: How do I disable freshness TTL?

A: To disable freshness TTL, you need to add the following code to your functions.php file:

add_filter( 'od_url_metric_freshness_ttl', function () { return -1; } );

Q: What are the benefits of disabling freshness TTL?

A: Disabling freshness TTL has several benefits. Firstly, it would allow URL metrics to remain fresh indefinitely as long as the ETags do not change, that is, if the state of the site does not change. Secondly, it would reduce the number of requests made to the server to update the URL metrics, which would improve the performance of the website.

Q: Is disabling freshness TTL a good idea?

A: Disabling freshness TTL is a good idea if you have a static website or a website with a small number of changes. However, if you have a dynamic website with frequent changes, disabling freshness TTL may not be the best idea.

Q: Can I use both freshness TTL and ETags to determine whether a URL metric is stale?

A: Yes, you can use both freshness TTL and ETags to determine whether a URL metric is stale. However, this would require modifying the OD_URL_Metric_Group class to use both freshness TTL and ETags.

Q: How do I modify the OD_URL_Metric_Group class to use both freshness TTL and ETags?

A: To modify the OD_URL_Metric_Group class to use both freshness TTL and ETags, you need to introduce a new filter od_url_metric_freshness_ttl that allows the freshness TTL to be set to a positive integer, and modify the OD_URL_Metric_Group class to use both freshness TTL and ETags.

Q: What are the implications of disabling freshness TTL?

A: Disabling freshness TTL would have several implications. Firstly, it would allow URL metrics to remain fresh indefinitely as long as the ETags do not change, that is, if the state of the site does not change. Secondly, it would reduce the number of requests made to the server to update the URL metrics, which would improve the performance of the website.

Q: Can I revert back to using freshness TTL alone to determine whether a URL metric is stale?

A: Yes, you can revert back to using freshness TTL alone to determine whether a URL metric is stale by removing the filter od_url_metric_freshness_ttl that sets the freshness TTL to -1.

Conclusion

In conclusion, disabling freshness TTL in favor of using ETags alone to determine whether a URL metric is stale is a beneficial feature that would improve the performance of the website. By answering some frequently asked questions about this feature, we hope to have provided you with a better understanding of how to implement this feature on your website.