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Posted to commits@devlake.apache.org by yu...@apache.org on 2022/10/14 10:17:04 UTC
[incubator-devlake-website] 01/02: docs: update lead time for changes
This is an automated email from the ASF dual-hosted git repository.
yumeng pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/incubator-devlake-website.git
commit 56741dc3924d9d41126a555857e33ef3f92fb261
Author: Startrekzky <ka...@merico.dev>
AuthorDate: Fri Oct 14 17:59:57 2022 +0800
docs: update lead time for changes
---
docs/Metrics/LeadTimeForChanges.md | 28 ++++++++++++++++++----------
1 file changed, 18 insertions(+), 10 deletions(-)
diff --git a/docs/Metrics/LeadTimeForChanges.md b/docs/Metrics/LeadTimeForChanges.md
index 6183ac975..7f6140f8e 100644
--- a/docs/Metrics/LeadTimeForChanges.md
+++ b/docs/Metrics/LeadTimeForChanges.md
@@ -16,16 +16,24 @@ DORA dashboard. See [live demo](https://grafana-lake.demo.devlake.io/grafana/d/q
## How is it calculated?
-This metric can be calculated in two ways:
-- If a deployment can be linked to PRs, then the lead time for changes of a deployment is the average cycle time of its associated PRs. For instance,
- - Compared to the previous deployment `deploy-1`, `deploy-2` deployed three new commits `commit-1`, `commit-2` and `commit-3`.
- - `commit-1` is linked to `pr-1`, `commit-2` is linked to `pr-2` and `pr-3`, `commit-3` is not linked to any PR. Then, `deploy-2` is associated with `pr-1`, `pr-2` and `pr-3`.
- - `Deploy-2`'s lead time for changes = average cycle time of `pr-1`, `pr-2` and `pr-3`.
-- If a deployment can't be linked to PRs, then the lead time for changes is computed based on its associated commits. For instance,
- - Compared to the previous deployment `deploy-1`, `deploy-2` deployed three new commits `commit-1`, `commit-2` and `commit-3`.
- - None of `commit-1`, `commit-2` and `commit-3` is linked to any PR.
- - Calculate each commit's lead time for changes, which equals to `deploy-2`'s deployed_at - commit's authored_date
- - `Deploy-2`'s Lead time for changes = average lead time for changes of `commit-1`, `commit-2` and `commit-3`.
+This metric is calculated by the median cycle time of the PRs deployed in a time range. A PR's cycle time is equal to the time a PR was deployed minus the PR's first commit's authored_date.
+
+
+
+See the picture above, there were three deployments in the last month: Deploy-1, Deploy-2 and Deploy-3. Six PRs were deployed during the same period.
+
+ Median Lead Time for Changes = The median cycle time of PR-1, PR-2, PR-3, PR-4, PR-5, PR-6
+
+The way to calculate PR cycle time:
+- PR-1 cycle time = Deploy-1's finished_date - PR-1's first commit's authored_date
+- PR-2 cycle time = Deploy-2's finished_date - PR-2's first commit's authored_date
+- PR-3 cycle time = Deploy-2's finished_date - PR-3's first commit's authored_date
+- PR-4 cycle time = Deploy-3's finished_date - PR-4's first commit's authored_date
+- PR-5 cycle time = Deploy-3's finished_date - PR-5's first commit's authored_date
+- PR-6 cycle time = Deploy-3's finished_date - PR-6's first commit's authored_date
+
+PR cycle time is pre-calculated when dora plugin is triggered. You can connect to DevLake's database and find it in the field `change_timespan` in [table.pull_requests](https://devlake.apache.org/docs/DataModels/DevLakeDomainLayerSchema/#pull_requests).
+
Below are the benchmarks for different development teams from Google's report. However, it's difficult to tell which group a team falls into when the team's median lead time for changes is `between one week and one month`. Therefore, DevLake provides its own benchmarks to address this problem: