Faster way to get number of days between two Dates?

[bluetech]

I have two Dates, and I want to get the number of days between them. This is the code I ended up with:

(date1 - date2).total(SpanTotal::from(Unit::Day).days_are_24_hours()).unwrap() as i64

with chrono I used

(date1 - date2).num_days()

A quick profile of a benchmark of my code (has some other logic) with perf shows the main culprit to be (sorry, perf doesn't know how to demangle this one)

37% _ZN4jiff5civil4date14DateArithmetic11checked_add17h35a9be00c5fbd75bE.577

chrono has

9%  chrono::naive::date::NaiveDate::add_days

I tried the following (which I'm not sure is correct)

date1.duration_since(date2).as_hours() / 24

but it's not faster (seems to use the same DateArithmetic::checked_add function).

Is there a faster way to get the number of days between two Dates?

[BurntSushi]

It's a little tricky to answer this question without an MRE (please include MREs whenever possible), but if you have two civil::Dates, then you don't need to call span.total() on their difference. You can just do (date1 - date2).get_days().

Chrono uses a different representation that requires NaiveDate::day to do arithmetic to return the day value. Jiff stores the day value as-is. But Jiff might need to do more work to compute the difference in days. So Jiff might be faster in some workloads while Chrono might be faster than others.

With that said, this aspect of Jiff hasn't really had much optimization work applied to it yet.

[bluetech]

I see! This makes the code simpler, but only slightly faster. So I suppose the jiff::civil::date::DateArithmetic::checked_add happens in the subtraction itself, not the total. I'll try to create an MRE with that.

[BurntSushi]

Thanks!

[bluetech]

Here is the MRE: https://github.com/bluetech/jiff-mre
Unfortunately it is obfuscated and not minimal, so I don't expect you to actually run it (maybe if you have a VM or sandbox), but it is realistic, including all surrounding logic.
The first commit is jiff, the second commit is chrono. The benchmark can be run with cargo bench.

[BurntSushi]

OK thanks, that helps a lot.

What do you actually do with the Date values? Would it make sense if Jiff provided a civil::UnixEpochDays? It would effectively provide the same civil::Date API, but use a "number of days since the Unix epoch" representation. That would make these "number of days" calculations quite a bit faster. It wouldn't match your epoch of course, but if you just stay in the UnixEpochDays representation, that will just be a little arithmetic.

But yeah, most of the time being spent here is converting between YYYY-MM-DD and Unix epoch days.

[bluetech]

Most of my uses of Date are not performance sensitive:

• Validate the value as a date
• Have a semantic type for it
• Serialize to DB, JSON, printing
• Some business logic - comparing, some manipulating, offsetting, etc.

But there is also a use case where I parse many millions of these at once, then I want it to be fast.

Would it make sense if Jiff provided a civil::UnixEpochDays?

It would make sense but I really think you shouldn't complicate the library just for this use case! If we choose to use jiff, I can implement this myself, basically validating and storing the int and provide accessors which lazily convert to Date.

[BurntSushi]

It definitely isn't just for your use case. :) It is something I've been thinking about: #132

[BurntSushi]

All righty, so I diced up your MRE a bit. And with #265, I'm able to use a Timestamp where you're using civil::DateTime. Along with a number of optimizations (that I'll land once I clean them up), Jiff is now a hair faster than Chrono for me on your benchmark. For Jiff:

[andrew@duff jiff-mre]$ cargo bench
   Compiling mre v0.0.0 (/home/andrew/clones/jiff-mre)
    Finished `bench` profile [optimized + debuginfo] target(s) in 1.23s
     Running benches/card.rs (target/release/deps/card-0874926a4cf03d17)
Gnuplot not found, using plotters backend
from_records            time:   [1.8517 µs 1.8533 µs 1.8551 µs]
                        change: [-35.177% -35.078% -34.982%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 13 outliers among 100 measurements (13.00%)
  1 (1.00%) low mild
  5 (5.00%) high mild
  7 (7.00%) high severe

to_records              time:   [2.5339 µs 2.5375 µs 2.5411 µs]
                        change: [-32.328% -32.122% -31.915%] (p = 0.00 < 0.05)
                        Performance has improved.
Found 10 outliers among 100 measurements (10.00%)
  1 (1.00%) low severe
  5 (5.00%) low mild
  4 (4.00%) high mild

And for Chrono:

[andrew@duff original]$ cargo bench
    Finished `bench` profile [optimized + debuginfo] target(s) in 0.06s
     Running benches/card.rs (target/release/deps/card-d3987d87ed011815)
Gnuplot not found, using plotters backend
from_records            time:   [1.8721 µs 1.8736 µs 1.8751 µs]
                        change: [+0.1402% +0.3400% +0.5914%] (p = 0.00 < 0.05)
                        Change within noise threshold.
Found 6 outliers among 100 measurements (6.00%)
  2 (2.00%) low severe
  1 (1.00%) low mild
  2 (2.00%) high mild
  1 (1.00%) high severe

to_records              time:   [2.7299 µs 2.7339 µs 2.7378 µs]
                        change: [-0.0722% +0.2028% +0.4671%] (p = 0.15 > 0.05)
                        No change in performance detected.
Found 3 outliers among 100 measurements (3.00%)
  1 (1.00%) low mild
  2 (2.00%) high mild

(Yes, I switched your benchmarks to Criterion. The bencher stuff is pretty bush league.)

Here's the full patch:

diff --git a/Cargo.lock b/Cargo.lock
index dc0adf4..e0f7d9c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3,16 +3,220 @@
 version = 4

 [[package]]
-name = "bencher"
-version = "0.1.5"
+name = "aho-corasick"
+version = "1.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7dfdb4953a096c551ce9ace855a604d702e6e62d77fac690575ae347571717f5"
+checksum = "8e60d3430d3a69478ad0993f19238d2df97c507009a52b3c10addcd7f6bcb916"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "anes"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4b46cbb362ab8752921c97e041f5e366ee6297bd428a31275b9fcf1e380f7299"
+
+[[package]]
+name = "anstyle"
+version = "1.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "55cc3b69f167a1ef2e161439aa98aed94e6028e5f9a59be9a6ffb47aef1651f9"
+
+[[package]]
+name = "autocfg"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ace50bade8e6234aa140d9a2f552bbee1db4d353f69b8217bc503490fc1a9f26"
+
+[[package]]
+name = "bumpalo"
+version = "3.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1628fb46dfa0b37568d12e5edd512553eccf6a22a78e8bde00bb4aed84d5bdbf"
+
+[[package]]
+name = "cast"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37b2a672a2cb129a2e41c10b1224bb368f9f37a2b16b612598138befd7b37eb5"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "ciborium"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42e69ffd6f0917f5c029256a24d0161db17cea3997d185db0d35926308770f0e"
+dependencies = [
+ "ciborium-io",
+ "ciborium-ll",
+ "serde",
+]
+
+[[package]]
+name = "ciborium-io"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05afea1e0a06c9be33d539b876f1ce3692f4afea2cb41f740e7743225ed1c757"
+
+[[package]]
+name = "ciborium-ll"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57663b653d948a338bfb3eeba9bb2fd5fcfaecb9e199e87e1eda4d9e8b240fd9"
+dependencies = [
+ "ciborium-io",
+ "half",
+]
+
+[[package]]
+name = "clap"
+version = "4.5.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8acebd8ad879283633b343856142139f2da2317c96b05b4dd6181c61e2480184"
+dependencies = [
+ "clap_builder",
+]
+
+[[package]]
+name = "clap_builder"
+version = "4.5.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f6ba32cbda51c7e1dfd49acc1457ba1a7dec5b64fe360e828acb13ca8dc9c2f9"
+dependencies = [
+ "anstyle",
+ "clap_lex",
+]
+
+[[package]]
+name = "clap_lex"
+version = "0.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f46ad14479a25103f283c0f10005961cf086d8dc42205bb44c46ac563475dca6"
+
+[[package]]
+name = "criterion"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2b12d017a929603d80db1831cd3a24082f8137ce19c69e6447f54f5fc8d692f"
+dependencies = [
+ "anes",
+ "cast",
+ "ciborium",
+ "clap",
+ "criterion-plot",
+ "is-terminal",
+ "itertools",
+ "num-traits",
+ "once_cell",
+ "oorandom",
+ "plotters",
+ "rayon",
+ "regex",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "tinytemplate",
+ "walkdir",
+]
+
+[[package]]
+name = "criterion-plot"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6b50826342786a51a89e2da3a28f1c32b06e387201bc2d19791f622c673706b1"
+dependencies = [
+ "cast",
+ "itertools",
+]
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9dd111b7b7f7d55b72c0a6ae361660ee5853c9af73f70c3c2ef6858b950e2e51"
+dependencies = [
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b82ac4a3c2ca9c3460964f020e1402edd5753411d7737aa39c3714ad1b5420e"
+dependencies = [
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
+
+[[package]]
+name = "crunchy"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "43da5946c66ffcc7745f48db692ffbb10a83bfe0afd96235c5c2a4fb23994929"
+
+[[package]]
+name = "either"
+version = "1.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
+
+[[package]]
+name = "half"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6dd08c532ae367adf81c312a4580bc67f1d0fe8bc9c460520283f4c0ff277888"
+dependencies = [
+ "cfg-if",
+ "crunchy",
+]
+
+[[package]]
+name = "hermit-abi"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fbf6a919d6cf397374f7dfeeea91d974c7c0a7221d0d0f4f20d859d329e53fcc"
+
+[[package]]
+name = "is-terminal"
+version = "0.4.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e19b23d53f35ce9f56aebc7d1bb4e6ac1e9c0db7ac85c8d1760c04379edced37"
+dependencies = [
+ "hermit-abi",
+ "libc",
+ "windows-sys",
+]
+
+[[package]]
+name = "itertools"
+version = "0.10.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b0fd2260e829bddf4cb6ea802289de2f86d6a7a690192fbe91b3f46e0f2c8473"
+dependencies = [
+ "either",
+]
+
+[[package]]
+name = "itoa"
+version = "1.0.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d75a2a4b1b190afb6f5425f10f6a8f959d2ea0b9c2b1d79553551850539e4674"

 [[package]]
 name = "jiff"
 version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ba926fdd8e5b5e7f9700355b0831d8c416afe94b014b1023424037a187c9c582"
 dependencies = [
  "log",
  "portable-atomic",
@@ -20,20 +224,91 @@ dependencies = [
  "serde",
 ]

+[[package]]
+name = "js-sys"
+version = "0.3.77"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1cfaf33c695fc6e08064efbc1f72ec937429614f25eef83af942d0e227c3a28f"
+dependencies = [
+ "once_cell",
+ "wasm-bindgen",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.169"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b5aba8db14291edd000dfcc4d620c7ebfb122c613afb886ca8803fa4e128a20a"
+
 [[package]]
 name = "log"
 version = "0.4.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "04cbf5b083de1c7e0222a7a51dbfdba1cbe1c6ab0b15e29fff3f6c077fd9cd9f"

+[[package]]
+name = "memchr"
+version = "2.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
+
 [[package]]
 name = "mre"
 version = "0.0.0"
 dependencies = [
- "bencher",
+ "criterion",
  "jiff",
 ]

+[[package]]
+name = "num-traits"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "once_cell"
+version = "1.20.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "945462a4b81e43c4e3ba96bd7b49d834c6f61198356aa858733bc4acf3cbe62e"
+
+[[package]]
+name = "oorandom"
+version = "11.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b410bbe7e14ab526a0e86877eb47c6996a2bd7746f027ba551028c925390e4e9"
+
+[[package]]
+name = "plotters"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5aeb6f403d7a4911efb1e33402027fc44f29b5bf6def3effcc22d7bb75f2b747"
+dependencies = [
+ "num-traits",
+ "plotters-backend",
+ "plotters-svg",
+ "wasm-bindgen",
+ "web-sys",
+]
+
+[[package]]
+name = "plotters-backend"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "df42e13c12958a16b3f7f4386b9ab1f3e7933914ecea48da7139435263a4172a"
+
+[[package]]
+name = "plotters-svg"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51bae2ac328883f7acdfea3d66a7c35751187f870bc81f94563733a154d7a670"
+dependencies = [
+ "plotters-backend",
+]
+
 [[package]]
 name = "portable-atomic"
 version = "1.10.0"
@@ -67,6 +342,76 @@ dependencies = [
  "proc-macro2",
 ]

+[[package]]
+name = "rayon"
+version = "1.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b418a60154510ca1a002a752ca9714984e21e4241e804d32555251faf8b78ffa"
+dependencies = [
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.12.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1465873a3dfdaa8ae7cb14b4383657caab0b3e8a0aa9ae8e04b044854c8dfce2"
+dependencies = [
+ "crossbeam-deque",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "regex"
+version = "1.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b544ef1b4eac5dc2db33ea63606ae9ffcfac26c1416a2806ae0bf5f56b201191"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.4.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "809e8dc61f6de73b46c85f4c96486310fe304c434cfa43669d7b40f711150908"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b15c43186be67a4fd63bee50d0303afffcef381492ebe2c5d87f324e1b8815c"
+
+[[package]]
+name = "rustversion"
+version = "1.0.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7c45b9784283f1b2e7fb61b42047c2fd678ef0960d4f6f1eba131594cc369d4"
+
+[[package]]
+name = "ryu"
+version = "1.0.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6ea1a2d0a644769cc99faa24c3ad26b379b786fe7c36fd3c546254801650e6dd"
+
+[[package]]
+name = "same-file"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93fc1dc3aaa9bfed95e02e6eadabb4baf7e3078b0bd1b4d7b6b0b68378900502"
+dependencies = [
+ "winapi-util",
+]
+
 [[package]]
 name = "serde"
 version = "1.0.217"
@@ -87,6 +432,18 @@ dependencies = [
  "syn",
 ]

+[[package]]
+name = "serde_json"
+version = "1.0.138"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d434192e7da787e94a6ea7e9670b26a036d0ca41e0b7efb2676dd32bae872949"
+dependencies = [
+ "itoa",
+ "memchr",
+ "ryu",
+ "serde",
+]
+
 [[package]]
 name = "syn"
 version = "2.0.98"
@@ -98,8 +455,178 @@ dependencies = [
  "unicode-ident",
 ]

+[[package]]
+name = "tinytemplate"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "be4d6b5f19ff7664e8c98d03e2139cb510db9b0a60b55f8e8709b689d939b6bc"
+dependencies = [
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a210d160f08b701c8721ba1c726c11662f877ea6b7094007e1ca9a1041945034"
+
+[[package]]
+name = "walkdir"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "29790946404f91d9c5d06f9874efddea1dc06c5efe94541a7d6863108e3a5e4b"
+dependencies = [
+ "same-file",
+ "winapi-util",
+]
+
+[[package]]
+name = "wasm-bindgen"
+version = "0.2.100"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1edc8929d7499fc4e8f0be2262a241556cfc54a0bea223790e71446f2aab1ef5"
+dependencies = [
+ "cfg-if",
+ "once_cell",
+ "rustversion",
+ "wasm-bindgen-macro",
+]
+
+[[package]]
+name = "wasm-bindgen-backend"
+version = "0.2.100"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2f0a0651a5c2bc21487bde11ee802ccaf4c51935d0d3d42a6101f98161700bc6"
+dependencies = [
+ "bumpalo",
+ "log",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.100"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7fe63fc6d09ed3792bd0897b314f53de8e16568c2b3f7982f468c0bf9bd0b407"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.100"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ae87ea40c9f689fc23f209965b6fb8a99ad69aeeb0231408be24920604395de"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-backend",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.100"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a05d73b933a847d6cccdda8f838a22ff101ad9bf93e33684f39c1f5f0eece3d"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "web-sys"
+version = "0.3.77"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "33b6dd2ef9186f1f2072e409e99cd22a975331a6b3591b12c764e0e55c60d5d2"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
+[[package]]
+name = "winapi-util"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf221c93e13a30d793f7645a0e7762c55d169dbb0a49671918a2319d289b10bb"
+dependencies = [
+ "windows-sys",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.59.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
+dependencies = [
+ "windows-targets",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
+dependencies = [
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
diff --git a/Cargo.toml b/Cargo.toml
index 33329eb..048b1d0 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,16 +2,23 @@
 name = "mre"
 edition = "2021"

+[lib]
+bench = false
+
+[patch.crates-io]
+jiff = { path = "/home/andrew/rust/jiff/pr" }
+
 [dependencies]
-bencher = { version = "0.1.5", default-features = false }
+# bencher = { version = "0.1.5", default-features = false }
+criterion = "0.5.1"
 jiff = { version = "0.2.0", default-features = false, features = ["alloc", "std", "tzdb-zoneinfo"] }

 [profile.release]
-debug = 1
-lto = true
+debug = true
+# lto = true

 [profile.bench]
-lto = true
+# lto = true

 [[bench]]
 name = "card"
diff --git a/benches/card.rs b/benches/card.rs
index cc9900a..b4b736f 100644
--- a/benches/card.rs
+++ b/benches/card.rs
@@ -1,23 +1,32 @@
-use bencher::{benchmark_group, benchmark_main, black_box, Bencher};
+// use bencher::{benchmark_group, benchmark_main, black_box, Bencher};
+use criterion::Criterion;

 static FULL_RECORDS: &str = include_str!("full.records");

-fn from_records(b: &mut Bencher) {
+fn from_records(c: &mut Criterion) {
     let records = FULL_RECORDS.parse::<mre::Records>().unwrap();
-    b.iter(|| {
-        let c = mre::CD::from_records(&records);
-        black_box(c);
+    c.bench_function(&format!("from_records"), |b| {
+        b.iter(|| {
+            let c = mre::CD::from_records(&records);
+            std::hint::black_box(c);
+        });
     });
 }

-fn to_records(b: &mut Bencher) {
+fn to_records(c: &mut Criterion) {
     let records = FULL_RECORDS.parse::<mre::Records>().unwrap();
     let card = mre::CD::from_records(&records);
-    b.iter(|| {
-        let r = card.to_records().unwrap();
-        black_box(r);
+
+    c.bench_function(&format!("to_records"), |b| {
+        b.iter(|| {
+            let r = card.to_records().unwrap();
+            std::hint::black_box(r);
+        });
     });
 }

-benchmark_group!(benches, from_records, to_records);
-benchmark_main!(benches);
+// benchmark_group!(benches, from_records, to_records);
+// benchmark_main!(benches);
+
+criterion::criterion_group!(benches, from_records, to_records,);
+criterion::criterion_main!(benches);
diff --git a/src/b.rs b/src/b.rs
index fdbc4e2..c828533 100644
--- a/src/b.rs
+++ b/src/b.rs
@@ -1,4 +1,4 @@
-use jiff::Zoned;
+use jiff::Timestamp;

 use crate::bits::{BitReader, BitWriter};
 use crate::consts::{Record, EC, EM, FC, L, P, RECORD_SIZE, RS};
@@ -18,9 +18,9 @@ pub struct B {
     pub B2: u8,
     pub B3: EM,
     pub B4: EC,
-    pub B5: Zoned,
+    pub B5: Timestamp,
     pub B6: bool,
-    pub B7: Zoned,
+    pub B7: Timestamp,
     pub B8: [P; 8],
     pub B9: Option<u16>,
     pub B10: Option<L>,
@@ -131,9 +131,9 @@ impl B {
         Bits8(4).to_bits(self.B2, bs)?;
         Bits8(4).to_bits(self.B3.0, bs)?;
         Bits8(4).to_bits(self.B4.0, bs)?;
-        TimeReal.to_bits(&self.B5, bs)?;
+        TimeReal.to_bits(self.B5, bs)?;
         Boolean.to_bits(self.B6, bs)?;
-        TimeReal.to_bits(&self.B7, bs)?;
+        TimeReal.to_bits(self.B7, bs)?;
         for &priority in &self.B8 {
             Bits8(4).to_bits(priority.0, bs)?;
         }
diff --git a/src/consts.rs b/src/consts.rs
index 58c4d66..f7d7efc 100644
--- a/src/consts.rs
+++ b/src/consts.rs
@@ -1,4 +1,4 @@
-use jiff::civil::{Date, DateTime};
+use jiff::{civil::Date, Timestamp};

 pub const RECORD_SIZE: usize = 29;
 pub type Record = [u8; RECORD_SIZE];
@@ -6,7 +6,7 @@ pub static EMPTY_RECORD: Record = [0_u8; RECORD_SIZE];

 pub const EPOCH_DATE: Date = Date::constant(1997, 1, 1);
 pub const MAX_DATE: Date = Date::constant(2041, 11, 9);
-pub const EPOCH_DATETIME: DateTime = DateTime::constant(1997, 1, 1, 0, 0, 0, 0);
+pub const EPOCH_DATETIME: Timestamp = Timestamp::constant(852076800, 0);

 #[derive(Copy, Clone, PartialEq, Eq, Debug, PartialOrd, Ord)]
 pub struct RS(pub u16);
diff --git a/src/datatype.rs b/src/datatype.rs
index bb11407..f61cd64 100644
--- a/src/datatype.rs
+++ b/src/datatype.rs
@@ -1,4 +1,4 @@
-use jiff::{civil::Date, tz::TimeZone, Span, Unit, Zoned};
+use jiff::{civil::Date, SignedDuration, Span, Timestamp};

 use crate::bits::{BitReader, BitWriter};
 use crate::consts::{EPOCH_DATE, EPOCH_DATETIME, MAX_DATE};
@@ -114,24 +114,18 @@ impl DateReverse {

 pub(crate) struct TimeReal;
 impl TimeReal {
-    pub(crate) fn from_bits(self, bs: &mut BitReader<'_>) -> Result<Zoned, ReadError> {
+    pub(crate) fn from_bits(self, bs: &mut BitReader<'_>) -> Result<Timestamp, ReadError> {
         let value = Bits32(30).from_bits(bs)?;
-        Ok((EPOCH_DATETIME + Span::new().seconds(value))
-            .to_zoned(TimeZone::UTC)
-            .unwrap())
+        Ok(EPOCH_DATETIME + SignedDuration::from_secs(value.into()))
     }

     pub(crate) fn to_bits(
         self,
-        datetime: &Zoned,
+        datetime: Timestamp,
         bs: &mut BitWriter<'_>,
     ) -> Result<(), WriteError> {
-        let Ok(value) =
-            (datetime - &EPOCH_DATETIME.to_zoned(TimeZone::UTC).unwrap()).total(Unit::Second)
-        else {
-            return Err(WriteError::date_out_of_range());
-        };
-        if value < 0.0 || value >= 2f64.powi(30) {
+        let value = datetime.duration_since(EPOCH_DATETIME).as_secs();
+        if value < 0 || value >= 2i64.pow(30) {
             return Err(WriteError::date_out_of_range());
         }
         bs.write(30, value as u32)?;

[bluetech]

Along with a number of optimizations (that I'll land once I clean them up), Jiff is now a hair faster than Chrono for me on your benchmark.

Wow, that's better than I had hoped for. Thanks for improving this. Once the changes are in git, I'll try them and report back!