Use original `Array#sum` when calculating Numeric sum.
This commit is related #24804 issue.
Issue #24804 reports `Array#sum` becomes much slower when
ActiveSupport is included.
This commit tries to use original method as far as possible.
```shell
$ cat array_sum.rb
class Array
alias core_sum sum
end
require 'benchmark/ips'
require 'active_support/core_ext/enumerable'
ary = [1.0] * 1_000_000
Benchmark.ips do |x|
x.report("core sum") { ary.core_sum }
x.report("AS's sum") { ary.sum }
x.compare!
end
$ bundle exec ruby -v -I lib array_sum.rb
ruby 2.4.0dev (2016-05-01 master 54867) [x86_64-darwin14]
Calculating -------------------------------------
core sum 4.000 i/100ms
AS's sum 5.000 i/100ms
-------------------------------------------------
core sum 50.492 (± 7.9%) i/s - 252.000
AS's sum 50.116 (± 6.0%) i/s - 250.000
Comparison:
core sum: 50.5 i/s
AS's sum: 50.1 i/s - 1.01x slower
```
Signed-off-by: Jeremy Daer <jeremydaer@gmail.com>
This commit undoes 54243fe.
Reason: Further investigation has shown the benefit is not so clear
generally speaking.
There is a long discussion and several benchmarks in the PR #24658
if you are interested in the details.
This can be an issue when TZInfo::TimeZone#current_period is refreshed
due to timezone period transition, but it's not reflected in
ActiveSupport::TimeZone object.
For example, on Sun, 26 Oct 2014 22:00 UTC, Moscow changed its TZ from
MSK +04:00 to MSK +03:00 (-1 hour). If ActiveSupport::TimeZone['Moscow']
happens to be initialized just before the timezone transition, it will
cache its stale utc_offset even after the timezone transition.
This commit removes cache and fixes this issue.
Signed-off-by: Jeremy Daer <jeremydaer@gmail.com>
To suppress warning ('warning: method redefined; discarding old sum')
remove the method before override it.
Signed-off-by: Jeremy Daer <jeremydaer@gmail.com>
Awaken waiting threads even if the current thread (the previously
exclusive thread) hadn't taken a share lock.
This only happens in code that wasn't run within an executor, since that
always take an outermost share lock.
Previously these methods could return either a DateTime or a Time
depending on how the ActiveSupport::TimeWithZone instance had
been constructed. Changing to always return an instance of Time
eliminates a possible stack level too deep error in to_time where
it was wrapping a DateTime instance.
As a consequence of this the internal time value is now always an
instance of Time in the UTC timezone, whether that's as the UTC
time directly or a representation of the local time in the timezone.
There should be no consequences of this internal change and if
there are it's a bug due to leaky abstractions.
`DateTime#getlocal` is newly added public API.
It's responsible is same as `DateTime#utc`, so `calculations.rb` is
a best plase to define this method.
For keeping consistency with `DateTime#utc`, defines `#localtime` and
defines `getlocal` as an alias method.
In Ruby 2.4 the `to_time` method for both `DateTime` and `Time` will
preserve the timezone of the receiver when converting to an instance
of `Time`. Since Rails 5.0 will support Ruby 2.2, 2.3 and later we
need to introduce a compatibility layer so that apps that upgrade do
not break. New apps will have a config initializer file that defaults
to match the new Ruby 2.4 behavior going forward.
For information about the changes to Ruby see:
https://bugs.ruby-lang.org/issues/12189https://bugs.ruby-lang.org/issues/12271Fixes#24617.
When you come here without context, it is important to hightlight that
checking the predicate is worthwhile due to the observation that blank
strings are often empty. So you complicate the code (which has a cost
in terms of readability and aesthetics), but statistically makes sense.
Then, you also need to explain why the second operand is so convoluted.
Otherwise, you wonder why this line is written precisely this way. That
is what code comments are for.
This commit updates `delegate` to use the keyword argument syntax added in Ruby 2. I left the `ArgumentError` when `to` is missing, because it better explains how to correctly use `delegate`. We could instead rely on the default `ArgumentError` that would be raised if `to` were a required keyword argument.
Follow up on 697384df36 (commitcomment-17184696).
The regex to detect a blank string `/\A[[:space:]]*\z/` will loop through every character in the string to ensure that all of them are a `:space:` type. We can invert this logic and instead look for any non-`:space:` characters. When that happens, we would return on the first character found and the regex engine does not need to keep looking.
Thanks @nellshamrell for the regex talk at LSRC.
By defining a "blank" string as any string that does not have a non-whitespace character (yes, double negative) we can get a substantial speed bump.
Also an inline regex is (barely) faster than a regex in a constant, since it skips the constant lookup. A regex literal is frozen by default.
```ruby
require 'benchmark/ips'
def string_generate
str = " abcdefghijklmnopqrstuvwxyz\t".freeze
str[rand(0..(str.length - 1))] * rand(0..23)
end
strings = 100.times.map { string_generate }
ALL_WHITESPACE_STAR = /\A[[:space:]]*\z/
Benchmark.ips do |x|
x.report('current regex ') { strings.each {|str| str.empty? || ALL_WHITESPACE_STAR === str } }
x.report('+ instead of * ') { strings.each {|str| str.empty? || /\A[[:space:]]+\z/ === str } }
x.report('not a non-whitespace char') { strings.each {|str| str.empty? || !(/[[:^space:]]/ === str) } }
x.compare!
end
# Warming up --------------------------------------
# current regex
# 1.744k i/100ms
# not a non-whitespace char
# 2.264k i/100ms
# Calculating -------------------------------------
# current regex
# 18.078k (± 8.9%) i/s - 90.688k
# not a non-whitespace char
# 23.580k (± 7.1%) i/s - 117.728k
# Comparison:
# not a non-whitespace char: 23580.3 i/s
# current regex : 18078.2 i/s - 1.30x slower
```
This makes the method roughly 30% faster `(23.580 - 18.078)/18.078 * 100`.
cc/ @fxn
See the rationale in the comment in this patch.
To benchmark this I ran a number of variations, ultimately narrowing to
require 'benchmark/ips'
str = ''
regexp = /\A[[:space:]]*\z/
Benchmark.ips do |x|
x.report('regexp') { regexp === str }
x.report('empty') { str.empty? || regexp === str }
x.compare!
end
This benchmark has consistently reported speedups around 3.5x:
Calculating -------------------------------------
regexp 69.197k i/100ms
empty 115.468k i/100ms
-------------------------------------------------
regexp 2. 6.3%) i/s - 13.839M
empty 9. 8.8%) i/s - 47.804M
Comparison:
empty: 9642607.6 i/s
regexp: 2768351.9 i/s - 3.48x slower
Sometimes even reaching 4x.
Running the same bechmark on strings of 10 or 100 characters (with
whitespace or present) has shown a slowdown of just about 1.01/1.02.
Marginal, we seem to have a worthwhile trade-off here.
That helper will return time zones for any country that tzdata knows about.
So it will be much simpler for non-US people to list own country time zones
in HTML selects or anywhere.
Ruby 2.4 introduces `Array#sum`, but it only supports numeric elements,
breaking our `Enumerable#sum` which supports arbitrary `Object#+`.
To fix, override `Array#sum` with our compatible implementation.
Native Ruby 2.4:
%w[ a b ].sum
# => TypeError: String can't be coerced into Fixnum
With `Enumerable#sum` shim:
%w[ a b ].sum
# => 'ab'
We tried shimming the fast path and falling back to the compatible path
if it fails, but that ends up slower even in simple causes due to the cost
of exception handling. Our only choice is to override the native `Array#sum`
with our `Enumerable#sum`.
```ruby
ActiveSupport::Duration.parse('P3Y6M4DT12H30M5S')
(3.years + 3.days).iso8601
```
Inspired by Arnau Siches' [ISO8601 gem](https://github.com/arnau/ISO8601/)
and rewritten by Andrey Novikov with suggestions from Andrew White. Test
data from the ISO8601 gem redistributed under MIT license.
(Will be used to support the PostgreSQL interval data type.)
Before this commit
`NoMethodError: undefined method `form_name' for Time:Class` is raised
when an invalid argument is passed.
It is better to raise `ArgumentError` and show list of valid arguments
to developers.
