buffer read and write #1581
buffer read and write #1581
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Codecov Report
Additional details and impacted files@@ Coverage Diff @@
## main #1581 +/- ##
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- Coverage 68.86% 68.85% -0.02%
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Files 120 120
Lines 13058 13072 +14
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+ Hits 8993 9001 +8
- Misses 4065 4071 +6 |
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Hey, if I understand correctly, this changes normal read/write to buffered, so that number of syscalls are reduced? |
Yes,serde_json read content from reader byte by byte,if without buffered,there are huge number of read syscalls.Similarly,serde_json will call write for every element. |
| let file = File::create(path)?; | ||
| let writer = BufWriter::new(file); | ||
| to_writer_pretty(writer, &spec)?; |
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Hey, I know this is a test, but should we not also add a writer.flush() at the end, like we have done at other places?
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https://doc.rust-lang.org/nightly/std/io/struct.BufWriter.html
It is critical to call flush before BufWriter is dropped. Though dropping will attempt to flush the contents of the buffer, any errors that happen in the process of dropping will be ignored. Calling flush ensures that the buffer is empty and thus dropping will not even attempt file operations.
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Yes, so we should add a flush call after to_writer_pretty like other places right?
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So can you update and push it, so we can go ahead and merge this?
Signed-off-by: zhuli <wanlisnx@gmail.com>
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Thanks a lot for making this improvement ! |
https://github.com/serde-rs/json/blob/0ebeede28a0d5f0f07f18124078f55d62b180a2d/src/ser.rs#L1540
https://github.com/serde-rs/json/blob/0ebeede28a0d5f0f07f18124078f55d62b180a2d/src/read.rs#L194
before:
write(3, "{", 1) = 1
write(3, "\n", 1) = 1
write(3, " ", 2) = 2
write(3, """, 1) = 1
write(3, "ociVersion", 10) = 10
write(3, """, 1) = 1
write(3, ": ", 2) = 2
write(3, """, 1) = 1
write(3, "1.0.2-dev", 9) = 9
write(3, """, 1) = 1
...
read(3, "{", 1) = 1
read(3, "\n", 1) = 1
read(3, " ", 1) = 1
read(3, " ", 1) = 1
read(3, """, 1) = 1
read(3, "o", 1) = 1
read(3, "c", 1) = 1
read(3, "i", 1) = 1
read(3, "V", 1) = 1
read(3, "e", 1) = 1
read(3, "r", 1) = 1
read(3, "s", 1) = 1
...
after:
read(3, "{\n "ociVersion": "1.0.2-dev",\n "..., 8192) = 3293
write(3, "{\n "ociVersion": "1.0.2-dev",\n "..., 3282) = 3282