Since #34864 removed explicit receiver to clarify the
purpose of `delegate_missing_to`, I think it will be
better to do the same a few lines above to easier figure
out that `delegate_missing_to` defines `method_missing`,
`respond_to_missing?` when comparing these examples.
Since Ruby 2.6.0 NilClass#to_d is returning `BigDecimal` 0.0, this
breaks `average` compatibility with prior Ruby versions. This patch
makes `average` return `nil` in all Ruby versions when there are no
rows.
`nil`, `Numeric`, and `String` are most basic objects which are passed
to `type_cast`. But now each `when *types_which_need_no_typecasting`
evaluation allocates extra two arrays, it makes `type_cast` slower.
The `types_which_need_no_typecasting` was introduced at #15351, but the
method isn't useful (never used any adapters) since all adapters
(sqlite3, mysql2, postgresql, oracle-enhanced, sqlserver) still
overrides the `_type_cast`.
Just expanding the method would make the `type_cast` 2x faster.
```ruby
module ActiveRecord
module TypeCastFast
def type_cast_fast(value, column = nil)
value = id_value_for_database(value) if value.is_a?(Base)
if column
value = type_cast_from_column(column, value)
end
_type_cast_fast(value)
rescue TypeError
to_type = column ? " to #{column.type}" : ""
raise TypeError, "can't cast #{value.class}#{to_type}"
end
private
def _type_cast_fast(value)
case value
when Symbol, ActiveSupport::Multibyte::Chars, Type::Binary::Data
value.to_s
when true then unquoted_true
when false then unquoted_false
# BigDecimals need to be put in a non-normalized form and quoted.
when BigDecimal then value.to_s("F")
when nil, Numeric, String then value
when Type::Time::Value then quoted_time(value)
when Date, Time then quoted_date(value)
else raise TypeError
end
end
end
end
conn = ActiveRecord::Base.connection
conn.extend ActiveRecord::TypeCastFast
Benchmark.ips do |x|
x.report("type_cast") { conn.type_cast("foo") }
x.report("type_cast_fast") { conn.type_cast_fast("foo") }
x.compare!
end
```
```
Warming up --------------------------------------
type_cast 58.733k i/100ms
type_cast_fast 101.364k i/100ms
Calculating -------------------------------------
type_cast 708.066k (± 5.9%) i/s - 3.583M in 5.080866s
type_cast_fast 1.424M (± 2.3%) i/s - 7.197M in 5.055860s
Comparison:
type_cast_fast: 1424240.0 i/s
type_cast: 708066.0 i/s - 2.01x slower
```
In an application that has a primary and replica database the data
inserted on the primary connection will not be able to be read by the
replica connection.
In a test like this:
```
test "creating a home and then reading it" do
home = Home.create!(owner: "eileencodes")
ActiveRecord::Base.connected_to(role: :default) do
assert_equal 3, Home.count
end
ActiveRecord::Base.connected_to(role: :readonly) do
assert_equal 3, Home.count
end
end
```
The home inserted in the beginning of the test can't be read by the
replica database because when the test is started a transasction is
opened byy `setup_fixtures`. That transaction remains open for the
remainder of the test until we are done and run `teardown_fixtures`.
Because the data isn't actually committed to the database the replica
database cannot see the data insertion.
I considered a couple ways to fix this. I could have written a database
cleaner like class that would allow the data to be committed and then
clean up that data afterwards. But database cleaners can make the
database slow and the point of the fixtures is to be fast.
In GitHub we solve this by sharing the connection pool for the replicas
with the primary (writing) connection. This is a bit hacky but it works.
Additionally since we define `replica? || preventing_writes?` as the
code that blocks writes to the database this will still prevent writing
on the replica / readonly connection. So we get all the behavior of
multiple connections for the same database without slowing down the
database.
In this PR the code loops through the handlers. If the handler doesn't
match the default handler then it retrieves the connection pool from the
default / writing handler and assigns the reading handler's connections
to that pool.
Then in enlist_fixture_connections it maps all the connections for the
default handler because all the connections are now available on that
handler so we don't need to loop through them again.
The test uses a temporary connection pool so we can test this with
sqlite3_mem. This adapter doesn't behave the same as the others and
after looking over how the query cache test works I think this is the
most correct. The issues comes when calling `connects_to` because that
establishes new connections and confuses the sqlite3_mem adapter. I'm
not entirely sure why but I wanted to make sure we tested all adapters
for this change and I checked that it wasn't the shared connection code
that was causing issues - it was the `connects_to` code.
That ability was introduced at #11898 as `Relation#update` without
giving ids, so the ability on the class level is not documented and not
tested.
c83e30d which fixes#33470 has lost two undocumented abilities.
One has fixed at 5c65688, but I missed the ability on the class level.
Removing any feature should not be suddenly happened in a stable version
even if that is not documented.
I've restored the ability and added test case to avoid any regression in
the future.
Fixes#34743.
This reverts 27c6c07 since `arel_attr.to_s` is not right way to avoid
the type error.
That to_s returns `"#<struct Arel::Attributes::Attribute ...>"`, there
is no reason to match the regex to the inspect form.
And also, the regex path is not covered by our test cases. I've tweaked
the regex for redundant part and added assertions for the regex path.
