0Dne 5.7.2016 v 16:10 Ademar Reis napsal(a):
On Fri, Jul 01, 2016 at 03:57:31PM +0200, Lukáš Doktor wrote:Dne 30.6.2016 v 22:57 Ademar Reis napsal(a):On Thu, Jun 30, 2016 at 06:59:39PM +0200, Lukáš Doktor wrote:Hello guys,the purpose of this RFC is to properly split and define the way test parameters are processed. There are several ways to split them apart, each with some benefits and drawbacks. Current params process ====================== `tree.TreeNode` -> Object allowing to store things (environment, filters, ...) in tree-structure `multiplexer.Mux` -> Interface between job and multiplexer. Reports number of tests and yields modified test_suite templates `multiplexer.MuxTree` -> Object representing part of the tree from the root to leaves or another multiplex domain. Recursively it creates multiplexed variants of the full tree. `multiplexer.AvocadoParams` -> Params object used to retrieve params from given path, allows defining several domains for relative paths matching defined as `mux_path`s. `multiplexer.AvocadoParam` -> Slice of the `AvocadoParams` which handles given `mux_path`. `test.Test.default_params` -> Dictionary which can define test's default values, it's intended for removal for some time. Creating variants ----------------- 1. app 2. parser -> creates the root tree `args.default_avocado_params = TreeNode()` 3. plugins.* -> inject key/value into `args.default_avocado_params` (or it's children). One example is `plugins.run`'s --mux-inject, the other is `avocado_virt`'s default values. 4. job -> creates multiplexer.Mux() object a. If "-m" specified, parses and filters the yaml file(s), otherwise creates an empty TreeNode() called `mux_tree` b. If `args.default_avocado_params` exists, it merges it into the `mux_tree` (no filtering of the default params) c. Initializes `multiplexer.MuxTree` object using the `mux_tree` 5. job -> asks the Mux() object for number of tests a. Mux iterates all MuxTree variants and reports `no_variants * no_tests` 6. runner -> iterates through test_suite a. runner -> iterates through Mux: i. multiplexer.Mux -> iterates through MuxTree * multiplexer.MuxTree -> yields list of leaves of the `mux_tree` ii, yields the modified test template b. runs the test template: i. Test.__init__: | if isinstance(params, dict): # update test's default params elif params is None: # New empty multiplexer.AvocadoParams are created elif isinstance(params, tuple): # multiplexer.AvocadoParams are created from params 7. exit AvocadoParams initialization ---------------------------- def __init__(self, leaves, test_id, tag, mux_path, default_params): """ :param leaves: List of TreeNode leaves defining current variant :param test_id: test id :param tag: test tag :param mux_path: list of entry points :param default_params: dict of params used when no matches found """ 1. Iterates through `mux_path` and creates `AvocadoParam` slices containing params from only matching nodes, storing them in `self._rel_paths` 2. Creates `AvocadoParam` slice containing the remaining params, storing them in `self._abs_path` Test params ----------- def get(self, key, path=None, default=None): """ Retrieve value associated with key from params :param key: Key you're looking for :param path: namespace ['*'] :param default: default value when not found :raise KeyError: In case of multiple different values (params clash) """ 1. Tries to obtain the (key, path, default) from cache 2. Tries to get the (key, path) from `self._rel_paths` 3. When the `path` is abs_path it tries to get the param from `self._abs_path` 4. Looks into the Test's default params dictionary 5. Returns `default` Overview -------- Basically now there are 3 components: 1. params parser (yaml => tree) 2. variants generator (tree => iterator) 3. test parameters (key => value from variant values) and we need to decide how do we want to split it and what should be part of the plugin API and what core API. Plugin parser->tree =================== We can say the `tree` is the actual params API and we could only allow producing custom parsers to construct the tree. This would be the simplest method as it only requires us to move the yaml parsing into the module and the `AvocadoParams` would stay as they are. The cons is that the plugin writers would only be able to produce params compatible with the tree structure (flat, or tree-like). If we decide to chose this method, we can keep the current avocado arguments and only allow replacing the parser plugin, eg. by `--multiplex-plugin NAME`. Alternatively we might even detect the suitable plugin based on the multiplex file and even allow combining them (`.cfg vs. .yaml, ...) The plugin would have to support: * parse_file(FILE) => tree_node * check_file(FILE) => BOOL // in case we want automatic detection of file->plugin Plugin parser->variant ====================== This would require deeper changes, but allow greater flexibility. We'd also have to chose whether we want to allow combinations, or whether the plugin should handle the whole workflow. I don't think we should allow combinations as that would imply another convention for storing the parsed results. The user would configure in config or on cmdline which plugin he wants to use and the arguments would stay the same (optionally extended by the plugin's arguments) The plugin would have to support: * configure(parser) // optional, add extended options like --mux-version * parse_file(FILE) // does not return as it's up to plugin to store the results * inject_value(key, value, path) // used by avocado-virt to inject default values * __len__() // Return number of variants (we might want to extend this to accept TEMPLATE and allow different number of variants per TEMPLATE. That is currently not supported, but it might be handy * itervariants(TEMPLATE) // yields modified TEMPLATE with params set in AvocadoParams understandable format Plugin AvocadoParams ==================== I don't think we should make the AvocadoParams replaceable, but if we want to we should strictly require `params.get` compatibility so all tests can run seamlessly with all params. Anyway if we decided to make AvocadoParams replaceable, then we can create a proxy between the params and the plugin. Conclusion ========== I'm looking forward to cleaner multiplexer API. I don't think people would like to invest much time in developing fancy multiplexer plugins so I'd go with the `parser->tree` variant, which allows easy extensibility with some level of flexibility. The flexibility is for example sufficient to implement cartesian_config parser. As for the automatic detection, I donẗ like the idea as people might want to use the same format with different custom tags.Hi Lukáš. I believe we're in sync, but I miss the high level overview, or at least review, of how params, variants and the multiplexer or other plugins are all related to each other. Please check the definitions/examples below to see if we're in sync: Params ------ A dictionary of key/values, with an optional path (we could simply call it prefix), which is used to identify the key when there are multiple versions of it. The path is interpreted from right to left to find a match. The Params data structure can be populated by multiple sources. Example: (implementation and API details are not discussed here) key: var1=a path: /foo/bar/baz key: var1=b path: /foo/bar key: var2=c path: NULL (empty) get(key=var1, path=/foo/) ==> error ("/foo/var1" not found) get(key=var1, path=/foo/*) ==> error (multiple var1) get(key=var1, path=/foo/bar/baz/weeee/) ==> error get(key=var1, path=/foo/bar/weeee/) ==> error get(key=var2) ==> c get(key=var2, path=foobar) ==> error ("foobar/var2" not found) get(key=var1, path=/foo/bar/baz/) ==> a (unique match for "/foo/bar/baz/var1") get(key=var1, path=/foo/bar/) ==> b (unique match for "/foo/bar/var1/") get(key=var1, path=baz) ==> a (unique match for "baz/var1") get(key=var1, path=bar) ==> b (unique match for "bar/var1") This kind of "get" API is exposed in the Test API. Variants -------- Multiple sets of params, all with the same set of keys and paths, but potentially different values. Each variant is identified by a "Variant ID" (see the "Test ID RFC"). The test runner is responsible for the association of tests and variants. That is, the component creating the variants has absolutely no visibility on which tests are going to be associated with variants. This is also completely abstract to tests: they don't have any visibility about which variant they're using, or which variants exist.Hello Ademar, Thank you for the overview, I probably should have included it. I omitted it as it's described in the documentation, so I only mentioned in the `Plugin AvocadoParams` that I don't think we should turn that part into a plugin. The variant, as described earlier, is the method which modifies the `test_template` and as you pointed out it compounds of `Variant ID` and `Params`. The way it works now it can go even further and alter all the test's arguments (name, methodName, params, base_logdir, tag, job, runner_queue) but it's not documented and might change in the future.OK, so I think we should change this. The layers should have clear responsibilities and abstractions, with variants being restricted to params only, as defined above. I don't think the component responsible for creating variants needs any visibility or knowledge about tests.
Yes, there is no need for that, it was only simplification:
https://github.com/avocado-framework/avocado/pull/1293
Given the above, the multiplexer (or any other component, like a "cartesian config" implementation from Autotest) would be bound to these APIs.The cartesian config is not related to params at all. Avocado-vt uses a hybrid mode and it replaces the params with their custom object, while keeping the `avocado` params in `test.avocado_params`. So in `avocado_vt` tests you don't have `self.params`, but you have `test.params` and `test.avocado_params`, where `test.params` is a dictionary and `test.avocado_params` the avocado params interface with path/key/value. Cartesian config produces variants not by creating test variants, but by adding multiple tests with different parameters to the test_suite.What I mean is that we probably could, in theory at least, implement a plugin that parses a "cartesian config" and provides the data as needed to fill the variants and param APIs I described above. I'm not saying we should do that, much less that it would be useful as a replacement for the current cartesian config implementation in avocado-vt. I'm simply stating that once we have a clear plugin API for Params and Variants, we should be able to replace the multiplexer with other mechanisms that provide a similar functionality. Thanks. - Ademar
In that case yes. You can see it in the conclusion that even the simpler version (parser->tree) is capable of using cartesian_config as source of params.
Regards, Lukáš
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