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diff --git a/doc/developer-guide/xlator-classification.md b/doc/developer-guide/xlator-classification.md new file mode 100644 index 00000000000..6073df9375f --- /dev/null +++ b/doc/developer-guide/xlator-classification.md @@ -0,0 +1,221 @@ +# xlator categories and expectations + +The purpose of the document is to define a category for various xlators +and expectations around what each category means from a perspective of +health and maintenance of a xlator. + +The need to do this is to ensure certain categories are kept in good +health, and helps the community and contributors focus their efforts around the +same. + +This document also provides implementation details for xlator developers to +declare a category for any xlator. + +## Table of contents +1. Audience +2. Categories (and expectations of each category) +3. Implementation and usage details + +## Audience + +This document is intended for the following community participants, +- New xlator contributors +- Existing xlator maintainers +- Packaging and gluster management stack maintainers + +For a more user facing understanding it is recommended to read section (TBD) +in the gluster documentation. + +## Categories +1. Experimental (E) +2. TechPreview (TP) +3. Maintained (M) +4. Deprecated (D) +5. Obsolete (O) + +### Experimental (E) + +Developed in the experimental branch, for exploring new features. These xlators +are NEVER packaged as a part of releases, interested users and contributors can +build and work with these from sources. In the future, these maybe available as +an package based on a weekly build of the same. + +#### Quality expectations +- Compiles or passes smoke tests +- Does not break nightly experimental regressions + - NOTE: If a nightly is broken, then all patches that were merged are reverted + till the errant patch is found and subsequently fixed + +### TechPreview (TP) + +Xlators in master or release branches that are not deemed fit to be in +production deployments, but are feature complete to invite feedback and host +user data. + +These xlators will be worked upon with priority by maintainers/authors who are +involved in making them more stable than xlators in the Experimental/Deprecated/ +Obsolete categories. + +There is no guarantee that these xlators will move to the Maintained state, and +may just get Obsoleted based on feedback, or other project goals or technical +alternatives. + +#### Quality expectations +- Same as Maintained, minus + - Performance, Scale, other(?) + - *TBD* *NOTE* Need inputs, Intention is all quality goals as in Maintained, + other than the list above (which for now has scale and performance) + +### Maintained (M) + +These xltors are part of the core Gluster functionality and are maintained +actively. These are part of master and release branches and are higher in +priority of maintainers and other interested contributors. + +#### Quality expectations + +NOTE: A short note on what each of these mean are added here, details to follow. + +NOTE: Out of the gate all of the following are not mandated, consider the +following a desirable state to reach as we progress on each + +- Bug backlog: Actively address bug backlog +- Enhancement backlog: Actively maintain outstanding enhancement backlog (need + not be acted on, but should be visible to all) +- Review backlog: Actively keep this below desired counts and states +- Static code health: Actively meet near-zero issues in this regard + - Coverity, spellcheck and other checks +- Runtime code health: Actively meet defined coverage levels in this regard + - Coverage, others? + - Per-patch regressions + - Glusto runs + - Performance + - Scalability +- Technical specifications: Implementation details should be documented and + updated at regular cadence (even per patch that change assumptions in + here) +- User documentation: User facing details should be maintained to current + status in the documentation +- Debuggability: Steps, tools, procedures should be documented and maintained + each release/patch as applicable +- Troubleshooting: Steps, tools, procedures should be documented and maintained + each release/patch as applicable + - Steps/guides for self service + - Knowledge base for problems +- Other common criteria that will apply: Required metrics/desired states to be + defined per criteria + - Monitoring, usability, statedump, and other such xlator expectations + +### Deprecated (D) + +Xlators on master or release branches that would be obsoleted and/or replaced +with similar or other functionality in the next major release. + +#### Quality expectations +- Retain status-quo when moved to this state, till it is moved to obsoleted +- Provide migration steps if feature provided by the xlator is replaced with +other xlators + +### Obsolete (O) + +Xlator/code still in tree, but not packaged or shipped or maintained in any +form. This is noted as a category till the code is removed from the tree. + +These xlators and their corresponding code and test health will not be executed. + +#### Quality expectations +- None + +## Implementation and usage details + +### How to specify an xlators category + +While defining 'xlator_api_t' structure for the corresponding xlator, add a +flag like below: + +``` +diff --git a/xlators/performance/nl-cache/src/nl-cache.c b/xlators/performance/nl-cache/src/nl-cache.c +index 0f0e53bac2..8267d6897c 100644 +--- a/xlators/performance/nl-cache/src/nl-cache.c ++++ b/xlators/performance/nl-cache/src/nl-cache.c +@@ -869,4 +869,5 @@ xlator_api_t xlator_api = { + .cbks = &nlc_cbks, + .options = nlc_options, + .identifier = "nl-cache", ++ .category = GF_TECH_PREVIEW, + }; +diff --git a/xlators/performance/quick-read/src/quick-read.c b/xlators/performance/quick-read/src/quick-read.c +index 8d39720e7f..235de27c19 100644 +--- a/xlators/performance/quick-read/src/quick-read.c ++++ b/xlators/performance/quick-read/src/quick-read.c +@@ -1702,4 +1702,5 @@ xlator_api_t xlator_api = { + .cbks = &qr_cbks, + .options = qr_options, + .identifier = "quick-read", ++ .category = GF_MAINTAINED, + }; +``` + +Similarly, if a particular option is in different state other than +the xlator state, one can add the same flag in options structure too. + +``` +diff --git a/xlators/cluster/afr/src/afr.c b/xlators/cluster/afr/src/afr.c +index 0e86e33d03..81996743d1 100644 +--- a/xlators/cluster/afr/src/afr.c ++++ b/xlators/cluster/afr/src/afr.c +@@ -772,6 +772,7 @@ struct volume_options options[] = { + .description = "Maximum latency for shd halo replication in msec." + }, + { .key = {"halo-enabled"}, ++ .category = GF_TECH_PREVIEW, + .type = GF_OPTION_TYPE_BOOL, + .default_value = "False", + +``` + + +### User experience using the categories + +#### Ability to use a category + +This section details which category of xlators can be used when and specifics +around when each category is enabled. + +1. Maintained category xlators can be used by default, this implies, volumes +created with these xlators enabled will throw no warnings, or need no user +intervention to use the xlator. + +2. Tech Preview category xlators needs cluster configuration changes to allow +these xlatorss to be used in volumes, further, logs will contain a message +stating TP xlators are in use. Without the cluster configured to allow TP +xlators, volumes created or edited to use such xlators would result in errors. + - (TBD) Cluster configuration option + - (TBD) Warning message + - (TBD) Code mechanics on how this is achieved + +3. Deprecated category xlators can be used by default, but will throw a warning +in the logs that such are in use and will be deprecated in the future. + - (TBD) Warning message + +4. Obsolete category xlators will not be packaged and hence cannot be used from +release builds. + +5. Experimental category xlators will not be packaged and hence cannot be used +from release builds, if running experimental (weekly or other such) builds, +these will throw a warning in the logs stating experimental xlators are in use. + - (TBD) Warning message + +#### Ability to query xlator category + +(TBD) Need to provide the ability to query xlator categories, or list xlators +and their respective categories. + +#### User facing changes + +User facing changes that are expected due to this change include the following, +- Cluster wide option to enable TP xlators, or more generically a category +level of xlators +- Errors in commands that fail due to invalid categories +- Warning messages in logs to denote certain categories of xlators are in use +- (TBD) Ability to query xlators and their respective categories |