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Updated summary for commit [612e0e2
](612e0e2160
) - While folks are welcome to read through the entire comments, the core information is summarized here. # Description This PR drastically improves startup times of Nushell by only parsing a single submodule of the Standard Library that provides the `banner` and `pwd` commands. All other Standard Library commands and submodules are parsed when imported by the user. This cuts startup times by more than 60%. At the moment, we have stopped adding to `std-lib` because every addition adds a small amount to the Nushell startup time. With this change, we should once again be able to allow new functionality to be added to the Standard Library without it impacting `nu` startup times. # User-Facing Changes * Nushell now starts about 60% faster * Breaking change: The `dirs` (Shells) aliases will return a warning message that it will not be auto-loaded in the following release, along with instructions on how to restore it (and disable the message) * The `use std <submodule> *` syntax is available for convenience, but should be avoided in scripts as it parses the entire `std` module and all other submodules and places it in scope. The correct syntax to *just* load a submodule is `use std/<submodule> *` (asterisk optional). The slash is important. This will be documented. * `use std *` can be used for convenience to load all of the library but still incurs the full loading-time. * `std/dirs`: Semi-breaking change. The `dirs` command replaces the `show` command. This is more in line with the directory-stack functionality found in other shells. Existing users will not be impacted by this as the alias (`shells`) remains the same. * Breaking-change: Technically a breaking change, but probably only impacts maintainers of `std`. The virtual path for the standard library has changed. It could previously be imported using its virtual path (and technically, this would have been the correct way to do it): ```nu use NU_STDLIB_VIRTUAL_DIR/std ``` The path is now simply `std/`: ```nu use std ``` All submodules have moved accordingly. # Timings Comparisons below were made: * In a temporary, clean config directory using `$env.XDG_CONFIG_HOME = (mktemp -d)`. * `nu` was run with a release build * `nu` was run one time to generate the default `config.nu` (etc.) files - Otherwise timings would include the user-prompt * The shell was exited and then restarted several times to get timing samples (Note: Old timings based on 0.97 rather than 0.98, but in the range of being accurate) | Scenario | `$nu.startup-time` | | --- | --- | | 0.97.2 ([aaaab8e
](aaaab8e070
)) Without this PR | 23ms - 24ms | | This PR with deprecated commands | 9ms - <11ms | | This PR after deprecated commands are removed in following release | 8ms - <10ms | | Final PR (remove deprecated), using `--no-std-lib` | 6.1ms to 6.4ms | | Final PR (remove deprecated), using `--no-config-file` | 3.1ms - 3.6ms | | Final PR (remove deprecated), using `--no-config-file --no-std-lib` | 1ms - 1.5ms | *These last two timings point to the opportunity for further optimization (see comment in thread below (will link once I write it).* # Implementation details for future maintenance * `use std banner` is a ridiculously deceptive call. That call parses and imports *all* of `std` into scope. Simply replacing it with `use std/core *` is essentially what saves ~14-15ms. This *only* imports the submodule with the `banner` and `pwd` commands. * From the code-comments, the reason that `NU_STDLIB_VIRTUAL_DIR` was used as a prefix was so that there wouldn't be an issue if a user had a `./std/mod.nu` in the current directory. This does **not** appear to be an issue. After removing the prefix, I tested with both a relative module as well as one in the `$env.NU_LIB_DIRS` path, and in all cases the *internal* `std` still took precedence. * By removing the prefix, users can now `use std` (and variants) without requiring that it already be parsed and in scope. * In the next release, we'll stop autoloading the `dirs` (shells) functionality. While this only costs an additional 1-1.5ms, I think it's better moved to the `config.nu` where the user can optionally remove it. The main reason is its use of aliases (which have also caused issues) - The `n`, `p`, and `g` short-commands are valuable real-estate, and users may want to map these to something else. For this release, there's an `deprecated_dirs` module that is still autoloaded. As with the top-level commands, use of these will give a deprecation warning with instructions on how to handle going forward. To help with this, moved the aliases to their own submodule inside the `dirs` module. * Also sneaks in a small change where the top-level `dirs` command is now the replacement for `dirs show` * Fixed a double-import of `assert` in `dirs.nu` * The `show_banner` step is replaced with simply `banner` rather than re-importing it. * A `virtual_path` may now be referenced with either a forward-slash or a backward-slash on Windows. This allows `use std/<submodule>` to work on all platforms. # Performance side-notes: * Future parsing and/or IR improvements should improve performance even further. * While the existing load time penalty of `std-lib` was not noticeable on many systems, Nushell runs on a wide-variety of hardware and OS platforms. Slower platforms will naturally see a bigger jump in performance here. For users starting multiple Nushell sessions frequently (e.g., `tmux`, Zellij, `screen`, et. al.) it is recommended to keep total startup time (including user configuration) under ~250ms. # Tests + Formatting * All tests are green * Updated tests: - Removed the test that confirmed that `std` was loaded (since we don't). - Removed the `shells` test since it is not autoloaded. Main `dirs.nu` functionality is tested through `stdlib-test`. - Many tests assumed that the library was fully loaded, because it was (even though we didn't intend for it to be). Fixed those tests. - Tests now import only the necessary submodules (e.g., `use std/assert`, rather than `use std assert`) - Some tests *thought* they were loading `std/log`, but were doing so improperly. This was masked by the now-fixed "load-everything-into-scope bug". Local CI would pass due the `$env.NU_LOG_<...>` variables being inherited from the calling process, but would fail in the "clean" GitHub CI environment. These tests have also been fixed. * Added additional tests for the changes # After Submitting Will update the Standard Library doc page
179 lines
5.6 KiB
Text
179 lines
5.6 KiB
Text
use std/assert
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use std/log
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# A couple of nuances to understand when testing module that exports environment:
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# Each 'use' for that module in the test script will execute the def --env block.
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# PWD at the time of the `use` will be what the export def --env block will see.
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#[before-each]
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def before-each [] {
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# need some directories to play with
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let base_path = ($nu.temp-path | path join $"test_dirs_(random uuid)")
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let path_a = ($base_path | path join "a")
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let path_b = ($base_path | path join "b")
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mkdir $base_path $path_a $path_b
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{base_path: $base_path, path_a: $path_a, path_b: $path_b}
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}
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#[after-each]
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def after-each [] {
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let base_path = $in.base_path
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cd $base_path
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cd ..
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rm -r $base_path
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}
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def cur_dir_check [expect_dir, scenario] {
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log debug $"check dir ($expect_dir), scenario ($scenario)"
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assert equal $expect_dir $env.PWD $"expected not PWD after ($scenario)"
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}
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def cur_ring_check [expect_dir:string, expect_position: int scenario:string] {
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log debug $"check ring ($expect_dir), position ($expect_position) scenario ($scenario)"
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assert ($expect_position < ($env.DIRS_LIST | length)) $"ring big enough after ($scenario)"
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assert equal $expect_position $env.DIRS_POSITION $"position in ring after ($scenario)"
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}
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#[test]
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def dirs_command [] {
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# careful with order of these statements!
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# must capture value of $in before executing `use`s
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let $c = $in
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# must set PWD *before* doing `use` that will run the def --env block in dirs module.
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cd $c.base_path
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# must execute these uses for the UOT commands *after* the test and *not* just put them at top of test module.
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# the def --env gets messed up
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use std/dirs
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# Stack: [BASE]
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assert equal [$c.base_path] $env.DIRS_LIST "list is just pwd after initialization"
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dirs next
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assert equal $c.base_path $env.DIRS_LIST.0 "next wraps at end of list"
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dirs prev
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assert equal $c.base_path $env.DIRS_LIST.0 "prev wraps at top of list"
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# Stack becomes: [base PATH_B path_a]
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dirs add $c.path_b $c.path_a
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assert equal $c.path_b $env.PWD "add changes PWD to first added dir"
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assert length $env.DIRS_LIST 3 "add in fact adds to list"
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assert equal $c.path_a $env.DIRS_LIST.2 "add in fact adds to list"
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# Stack becomes: [BASE path_b path_a]
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dirs next 2
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# assert (not) equal requires span.start of first arg < span.end of 2nd
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assert equal $env.PWD $c.base_path "next wraps at end of list"
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# Stack becomes: [base path_b PATH_A]
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dirs prev 1
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assert equal $c.path_a $env.PWD "prev wraps at start of list"
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cur_dir_check $c.path_a "prev wraps to end from start of list"
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# Stack becomes: [base PATH_B]
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dirs drop
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assert length $env.DIRS_LIST 2 "drop removes from list"
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assert equal $env.PWD $c.path_b "drop changes PWD to previous in list (before dropped element)"
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assert equal (dirs) [[active path]; [false $c.base_path] [true $c.path_b]] "show table contains expected information"
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# Stack becomes: [BASE]
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dirs drop
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assert length $env.DIRS_LIST 1 "drop removes from list"
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assert equal $env.PWD $c.base_path "drop changes PWD (regression test for #9449)"
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}
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#[test]
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def dirs_next [] {
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# must capture value of $in before executing `use`s
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let $c = $in
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# must set PWD *before* doing `use` that will run the def --env block in dirs module.
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cd $c.base_path
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assert equal $env.PWD $c.base_path "test setup"
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use std/dirs
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cur_dir_check $c.base_path "use module test setup"
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dirs add $c.path_a $c.path_b
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cur_ring_check $c.path_a 1 "add 2, but pwd is first one added"
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dirs next
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cur_ring_check $c.path_b 2 "next to third"
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dirs next
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cur_ring_check $c.base_path 0 "next from top wraps to bottom of ring"
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}
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#[test]
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def dirs_cd [] {
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# must capture value of $in before executing `use`s
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let $c = $in
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# must set PWD *before* doing `use` that will run the def --env block in dirs module.
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cd $c.base_path
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use std/dirs
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cur_dir_check $c.base_path "use module test setup"
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cd $c.path_b
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cur_ring_check $c.path_b 0 "cd with empty ring"
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dirs add $c.path_a
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cur_dir_check $c.path_a "can add 2nd directory"
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cd $c.path_b
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cur_ring_check $c.path_b 1 "cd at 2nd item on ring"
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dirs next
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cur_ring_check $c.path_b 0 "cd updates current position in non-empty ring"
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assert equal [$c.path_b $c.path_b] $env.DIRS_LIST "cd updated both positions in ring"
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}
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#[test]
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def dirs_goto_bug10696 [] {
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let $c = $in
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cd $c.base_path
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use std/dirs
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dirs add $c.path_a
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cd $c.path_b
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dirs goto 0
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dirs goto 1
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assert equal $env.PWD $c.path_b "goto other, then goto to come back returns to same directory"
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}
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#[test]
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def dirs_goto [] {
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let $c = $in
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cd $c.base_path
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use std/dirs
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# check that goto can move *from* any position in the ring *to* any other position (correctly)
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assert equal $env.PWD $c.base_path
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dirs add $c.path_a
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dirs add $c.path_b
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assert equal ($env.DIRS_LIST | length) 3 "start with 3 elements in ring"
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let exp_dir = [$c.base_path $c.path_a $c.path_b]
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for $cur_pos in 0..<($env.DIRS_LIST | length) {
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for $other_pos in 0..<($env.DIRS_LIST | length) {
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dirs goto $cur_pos
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assert equal $env.PWD ($exp_dir | get $cur_pos) "initial position as expected"
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dirs goto $other_pos
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assert equal $env.DIRS_POSITION $other_pos "goto moved index to correct slot"
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assert equal $env.PWD ($exp_dir | get $other_pos) "goto changed working directory correctly"
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}
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}
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# check that 'dirs goto' with no argument maps to `dirs` (main)
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assert length (dirs goto) 3
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}
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