CL 72150 fixes#22352 by reverting the problematic parts of that CL
where the line number and column number were inconsistent with each other.
This CL adds back functionality to address the issue that CL 72150
was trying to solve in the first place. That is, it reports the starting
line of the record, so that users have a frame of reference to start with
when debugging what went wrong.
In the event of gnarly CSV files with multiline quoted strings, a parse
failure likely occurs somewhere between the start of the record and
the point where the parser finally detected an error.
Since ParserError.{Line,Column} reports where the *error* occurs, we
add a RecordLine field to report where the record starts.
Also take this time to cleanup and modernize TestRead.
Fixes#19019Fixes#22352
Change-Id: I16cebf0b81922c35f75804c7073e9cddbfd11a04
Reviewed-on: https://go-review.googlesource.com/72310
Reviewed-by: Ian Lance Taylor <iant@golang.org>
The Reader implementation is slow because it operates on a rune-by-rune
basis via bufio.Reader.ReadRune. We speed this up by operating on entire
lines that we read from bufio.Reader.ReadSlice.
In order to ensure that we read the full line, we augment ReadSlice
in our Reader.readLine method to automatically expand the slice if
bufio.ErrBufferFull is every hit.
This change happens to fix#19410 because it no longer relies on
rune-by-rune parsing and only searches for the relevant delimiter rune.
In order to keep column accounting simple and consistent, this change
reverts parts of CL 52830.
This CL is an alternative to CL 36270 and builds on some of the ideas
from that change by Diogo Pinela.
name old time/op new time/op delta
Read-8 3.12µs ± 1% 2.54µs ± 2% -18.76% (p=0.000 n=10+9)
ReadWithFieldsPerRecord-8 3.12µs ± 1% 2.53µs ± 1% -18.91% (p=0.000 n=9+9)
ReadWithoutFieldsPerRecord-8 3.13µs ± 0% 2.57µs ± 3% -18.07% (p=0.000 n=10+10)
ReadLargeFields-8 52.3µs ± 1% 5.3µs ± 2% -89.93% (p=0.000 n=10+9)
ReadReuseRecord-8 2.05µs ± 1% 1.40µs ± 1% -31.48% (p=0.000 n=10+9)
ReadReuseRecordWithFieldsPerRecord-8 2.05µs ± 1% 1.41µs ± 0% -31.03% (p=0.000 n=10+9)
ReadReuseRecordWithoutFieldsPerRecord-8 2.06µs ± 1% 1.40µs ± 1% -31.70% (p=0.000 n=9+10)
ReadReuseRecordLargeFields-8 50.9µs ± 0% 4.1µs ± 3% -92.01% (p=0.000 n=10+10)
name old alloc/op new alloc/op
Read-8 664B ± 0% 664B ± 0%
ReadWithFieldsPerRecord-8 664B ± 0% 664B ± 0%
ReadWithoutFieldsPerRecord-8 664B ± 0% 664B ± 0%
ReadLargeFields-8 3.94kB ± 0% 3.94kB ± 0%
ReadReuseRecord-8 24.0B ± 0% 24.0B ± 0%
ReadReuseRecordWithFieldsPerRecord-8 24.0B ± 0% 24.0B ± 0%
ReadReuseRecordWithoutFieldsPerRecord-8 24.0B ± 0% 24.0B ± 0%
ReadReuseRecordLargeFields-8 2.98kB ± 0% 2.98kB ± 0%
name old allocs/op new allocs/op
Read-8 18.0 ± 0% 18.0 ± 0%
ReadWithFieldsPerRecord-8 18.0 ± 0% 18.0 ± 0%
ReadWithoutFieldsPerRecord-8 18.0 ± 0% 18.0 ± 0%
ReadLargeFields-8 24.0 ± 0% 24.0 ± 0%
ReadReuseRecord-8 8.00 ± 0% 8.00 ± 0%
ReadReuseRecordWithFieldsPerRecord-8 8.00 ± 0% 8.00 ± 0%
ReadReuseRecordWithoutFieldsPerRecord-8 8.00 ± 0% 8.00 ± 0%
ReadReuseRecordLargeFields-8 12.0 ± 0% 12.0 ± 0%
Updates #22352
Updates #19019Fixes#16791Fixes#19410
Change-Id: I31c27cfcc56880e6abac262f36c947179b550bbf
Reviewed-on: https://go-review.googlesource.com/72150
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The parser mistakenly assumed it could always fold \r\n into \n, which
is not true since a \r\n inside a quoted fields has no special meaning
and should be kept as is.
Fix this by not folding \r\n to \n inside quotes fields.
Fixes#21201
Change-Id: Ifebc302e49cf63e0a027ee90f088dbc050a2b7a6
Reviewed-on: https://go-review.googlesource.com/52810
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Errors returned by Reader contain the line where the Reader originally
encountered the error. This can be suboptimal since that line does not
always correspond with the line the current record/field started at.
This can easily happen with LazyQuotes as seen in #19019, but also
happens for example when a quoted fields has no closing quote and
the parser hits EOF before it finds another quote.
When this happens finding the erroneous field can be somewhat
complicated and time consuming, and in most cases it would be better to
report the line where the record started.
This change updates Reader to keep track of the line on which a record
begins and uses it for errors instead of the current line, making it
easier to find errors.
Although a user-visible change, this should have no impact on existing
code, since most users don't explicitly work with the line in the error
and probably already expect the new behaviour.
Updates #19019
Change-Id: Ic9bc70fad2651c69435d614d537e7a9266819b05
Reviewed-on: https://go-review.googlesource.com/52830
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
In many cases the records returned by Reader.Read will only be used between calls
to Read and become garbage once a new record is read. In this case, instead of
allocating a new slice on each call to Read, we can reuse the last allocated slice
for successive calls to avoid unnecessary allocations.
This change adds a new field ReuseRecord to the Reader struct to enable this reuse.
ReuseRecord is false by default to avoid breaking existing code which dependss on
the current behaviour.
I also added 4 new benchmarks, corresponding to the existing Read benchmarks, which
set ReuseRecord to true.
Benchstat on my local machine (old is ReuseRecord = false, new is ReuseRecord = true)
name old time/op new time/op delta
Read-8 2.75µs ± 2% 1.88µs ± 1% -31.52% (p=0.000 n=14+15)
ReadWithFieldsPerRecord-8 2.75µs ± 0% 1.89µs ± 1% -31.43% (p=0.000 n=13+13)
ReadWithoutFieldsPerRecord-8 2.77µs ± 1% 1.88µs ± 1% -32.06% (p=0.000 n=15+15)
ReadLargeFields-8 55.4µs ± 1% 54.2µs ± 0% -2.07% (p=0.000 n=15+14)
name old alloc/op new alloc/op delta
Read-8 664B ± 0% 24B ± 0% -96.39% (p=0.000 n=15+15)
ReadWithFieldsPerRecord-8 664B ± 0% 24B ± 0% -96.39% (p=0.000 n=15+15)
ReadWithoutFieldsPerRecord-8 664B ± 0% 24B ± 0% -96.39% (p=0.000 n=15+15)
ReadLargeFields-8 3.94kB ± 0% 2.98kB ± 0% -24.39% (p=0.000 n=15+15)
name old allocs/op new allocs/op delta
Read-8 18.0 ± 0% 8.0 ± 0% -55.56% (p=0.000 n=15+15)
ReadWithFieldsPerRecord-8 18.0 ± 0% 8.0 ± 0% -55.56% (p=0.000 n=15+15)
ReadWithoutFieldsPerRecord-8 18.0 ± 0% 8.0 ± 0% -55.56% (p=0.000 n=15+15)
ReadLargeFields-8 24.0 ± 0% 12.0 ± 0% -50.00% (p=0.000 n=15+15)
Fixes#19721
Change-Id: I79b14128bb9bb3465f53f40f93b1b528a9da6f58
Reviewed-on: https://go-review.googlesource.com/41730
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Benchmarks broken off from https://golang.org/cl/24723 and modified to
allocate less in the places we're not trying to measure.
Updates #16791
Change-Id: I508e4cfeac60322d56f1d71ff1912f6a6f183a63
Reviewed-on: https://go-review.googlesource.com/30357
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently parseRecord will always start with a nil
slice and then resize the slice on append. For input
with a fixed number of fields per record we can preallocate
the slice to avoid having to resize the slice.
This change implements this optimization by using
FieldsPerRecord as capacity if it's > 0 and also adds a
benchmark to better show the differences.
benchmark old ns/op new ns/op delta
BenchmarkRead 19741 17909 -9.28%
benchmark old allocs new allocs delta
BenchmarkRead 59 41 -30.51%
benchmark old bytes new bytes delta
BenchmarkRead 6276 5844 -6.88%
Change-Id: I7c2abc9c80a23571369bcfcc99a8ffc474eae7ab
Reviewed-on: https://go-review.googlesource.com/8880
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
