compiler/rustc_serialize/src/opaque.rs

   1 use crate::leb128::{self, max_leb128_len};
   2 use crate::serialize::{Decodable, Decoder, Encodable, Encoder};
   3 use std::convert::TryInto;
   4 use std::fs::File;
   5 use std::io::{self, Write};
   6 use std::mem::MaybeUninit;
   7 use std::path::Path;
   8 use std::ptr;
   9
  10 // -----------------------------------------------------------------------------
  11 // Encoder
  12 // -----------------------------------------------------------------------------
  13
  14 pub struct MemEncoder {
  15     pub data: Vec<u8>,
  16 }
  17
  18 impl MemEncoder {
  19     pub fn new() -> MemEncoder {
  20         MemEncoder { data: vec![] }
  21     }
  22
  23     #[inline]
  24     pub fn position(&self) -> usize {
  25         self.data.len()
  26     }
  27
  28     pub fn finish(self) -> Vec<u8> {
  29         self.data
  30     }
  31 }
  32
  33 macro_rules! write_leb128 {
  34     ($enc:expr, $value:expr, $int_ty:ty, $fun:ident) => {{
  35         const MAX_ENCODED_LEN: usize = max_leb128_len!($int_ty);
  36         let old_len = $enc.data.len();
  37
  38         if MAX_ENCODED_LEN > $enc.data.capacity() - old_len {
  39             $enc.data.reserve(MAX_ENCODED_LEN);
  40         }
  41
  42         // SAFETY: The above check and `reserve` ensures that there is enough
  43         // room to write the encoded value to the vector's internal buffer.
  44         unsafe {
  45             let buf = &mut *($enc.data.as_mut_ptr().add(old_len)
  46                 as *mut [MaybeUninit<u8>; MAX_ENCODED_LEN]);
  47             let encoded = leb128::$fun(buf, $value);
  48             $enc.data.set_len(old_len + encoded.len());
  49         }
  50     }};
  51 }
  52
  53 /// A byte that [cannot occur in UTF8 sequences][utf8]. Used to mark the end of a string.
  54 /// This way we can skip validation and still be relatively sure that deserialization
  55 /// did not desynchronize.
  56 ///
  57 /// [utf8]: https://en.wikipedia.org/w/index.php?title=UTF-8&oldid=1058865525#Codepage_layout
  58 const STR_SENTINEL: u8 = 0xC1;
  59
  60 impl Encoder for MemEncoder {
  61     #[inline]
  62     fn emit_usize(&mut self, v: usize) {
  63         write_leb128!(self, v, usize, write_usize_leb128)
  64     }
  65
  66     #[inline]
  67     fn emit_u128(&mut self, v: u128) {
  68         write_leb128!(self, v, u128, write_u128_leb128);
  69     }
  70
  71     #[inline]
  72     fn emit_u64(&mut self, v: u64) {
  73         write_leb128!(self, v, u64, write_u64_leb128);
  74     }
  75
  76     #[inline]
  77     fn emit_u32(&mut self, v: u32) {
  78         write_leb128!(self, v, u32, write_u32_leb128);
  79     }
  80
  81     #[inline]
  82     fn emit_u16(&mut self, v: u16) {
  83         self.data.extend_from_slice(&v.to_le_bytes());
  84     }
  85
  86     #[inline]
  87     fn emit_u8(&mut self, v: u8) {
  88         self.data.push(v);
  89     }
  90
  91     #[inline]
  92     fn emit_isize(&mut self, v: isize) {
  93         write_leb128!(self, v, isize, write_isize_leb128)
  94     }
  95
  96     #[inline]
  97     fn emit_i128(&mut self, v: i128) {
  98         write_leb128!(self, v, i128, write_i128_leb128)
  99     }
 100
 101     #[inline]
 102     fn emit_i64(&mut self, v: i64) {
 103         write_leb128!(self, v, i64, write_i64_leb128)
 104     }
 105
 106     #[inline]
 107     fn emit_i32(&mut self, v: i32) {
 108         write_leb128!(self, v, i32, write_i32_leb128)
 109     }
 110
 111     #[inline]
 112     fn emit_i16(&mut self, v: i16) {
 113         self.data.extend_from_slice(&v.to_le_bytes());
 114     }
 115
 116     #[inline]
 117     fn emit_i8(&mut self, v: i8) {
 118         self.emit_u8(v as u8);
 119     }
 120
 121     #[inline]
 122     fn emit_bool(&mut self, v: bool) {
 123         self.emit_u8(if v { 1 } else { 0 });
 124     }
 125
 126     #[inline]
 127     fn emit_f64(&mut self, v: f64) {
 128         let as_u64: u64 = v.to_bits();
 129         self.emit_u64(as_u64);
 130     }
 131
 132     #[inline]
 133     fn emit_f32(&mut self, v: f32) {
 134         let as_u32: u32 = v.to_bits();
 135         self.emit_u32(as_u32);
 136     }
 137
 138     #[inline]
 139     fn emit_char(&mut self, v: char) {
 140         self.emit_u32(v as u32);
 141     }
 142
 143     #[inline]
 144     fn emit_str(&mut self, v: &str) {
 145         self.emit_usize(v.len());
 146         self.emit_raw_bytes(v.as_bytes());
 147         self.emit_u8(STR_SENTINEL);
 148     }
 149
 150     #[inline]
 151     fn emit_raw_bytes(&mut self, s: &[u8]) {
 152         self.data.extend_from_slice(s);
 153     }
 154 }
 155
 156 pub type FileEncodeResult = Result<usize, io::Error>;
 157
 158 // `FileEncoder` encodes data to file via fixed-size buffer.
 159 //
 160 // When encoding large amounts of data to a file, using `FileEncoder` may be
 161 // preferred over using `MemEncoder` to encode to a `Vec`, and then writing the
 162 // `Vec` to file, as the latter uses as much memory as there is encoded data,
 163 // while the former uses the fixed amount of memory allocated to the buffer.
 164 // `FileEncoder` also has the advantage of not needing to reallocate as data
 165 // is appended to it, but the disadvantage of requiring more error handling,
 166 // which has some runtime overhead.
 167 pub struct FileEncoder {
 168     // The input buffer. For adequate performance, we need more control over
 169     // buffering than `BufWriter` offers. If `BufWriter` ever offers a raw
 170     // buffer access API, we can use it, and remove `buf` and `buffered`.
 171     buf: Box<[MaybeUninit<u8>]>,
 172     buffered: usize,
 173     flushed: usize,
 174     file: File,
 175     // This is used to implement delayed error handling, as described in the
 176     // comment on `trait Encoder`.
 177     res: Result<(), io::Error>,
 178 }
 179
 180 impl FileEncoder {
 181     pub fn new<P: AsRef<Path>>(path: P) -> io::Result<Self> {
 182         const DEFAULT_BUF_SIZE: usize = 8192;
 183         FileEncoder::with_capacity(path, DEFAULT_BUF_SIZE)
 184     }
 185
 186     pub fn with_capacity<P: AsRef<Path>>(path: P, capacity: usize) -> io::Result<Self> {
 187         // Require capacity at least as large as the largest LEB128 encoding
 188         // here, so that we don't have to check or handle this on every write.
 189         assert!(capacity >= max_leb128_len());
 190
 191         // Require capacity small enough such that some capacity checks can be
 192         // done using guaranteed non-overflowing add rather than sub, which
 193         // shaves an instruction off those code paths (on x86 at least).
 194         assert!(capacity <= usize::MAX - max_leb128_len());
 195
 196         let file = File::create(path)?;
 197
 198         Ok(FileEncoder {
 199             buf: Box::new_uninit_slice(capacity),
 200             buffered: 0,
 201             flushed: 0,
 202             file,
 203             res: Ok(()),
 204         })
 205     }
 206
 207     #[inline]
 208     pub fn position(&self) -> usize {
 209         // Tracking position this way instead of having a `self.position` field
 210         // means that we don't have to update the position on every write call.
 211         self.flushed + self.buffered
 212     }
 213
 214     pub fn flush(&mut self) {
 215         // This is basically a copy of `BufWriter::flush`. If `BufWriter` ever
 216         // offers a raw buffer access API, we can use it, and remove this.
 217
 218         /// Helper struct to ensure the buffer is updated after all the writes
 219         /// are complete. It tracks the number of written bytes and drains them
 220         /// all from the front of the buffer when dropped.
 221         struct BufGuard<'a> {
 222             buffer: &'a mut [u8],
 223             encoder_buffered: &'a mut usize,
 224             encoder_flushed: &'a mut usize,
 225             flushed: usize,
 226         }
 227
 228         impl<'a> BufGuard<'a> {
 229             fn new(
 230                 buffer: &'a mut [u8],
 231                 encoder_buffered: &'a mut usize,
 232                 encoder_flushed: &'a mut usize,
 233             ) -> Self {
 234                 assert_eq!(buffer.len(), *encoder_buffered);
 235                 Self { buffer, encoder_buffered, encoder_flushed, flushed: 0 }
 236             }
 237
 238             /// The unwritten part of the buffer
 239             fn remaining(&self) -> &[u8] {
 240                 &self.buffer[self.flushed..]
 241             }
 242
 243             /// Flag some bytes as removed from the front of the buffer
 244             fn consume(&mut self, amt: usize) {
 245                 self.flushed += amt;
 246             }
 247
 248             /// true if all of the bytes have been written
 249             fn done(&self) -> bool {
 250                 self.flushed >= *self.encoder_buffered
 251             }
 252         }
 253
 254         impl Drop for BufGuard<'_> {
 255             fn drop(&mut self) {
 256                 if self.flushed > 0 {
 257                     if self.done() {
 258                         *self.encoder_flushed += *self.encoder_buffered;
 259                         *self.encoder_buffered = 0;
 260                     } else {
 261                         self.buffer.copy_within(self.flushed.., 0);
 262                         *self.encoder_flushed += self.flushed;
 263                         *self.encoder_buffered -= self.flushed;
 264                     }
 265                 }
 266             }
 267         }
 268
 269         // If we've already had an error, do nothing. It'll get reported after
 270         // `finish` is called.
 271         if self.res.is_err() {
 272             return;
 273         }
 274
 275         let mut guard = BufGuard::new(
 276             unsafe { MaybeUninit::slice_assume_init_mut(&mut self.buf[..self.buffered]) },
 277             &mut self.buffered,
 278             &mut self.flushed,
 279         );
 280
 281         while !guard.done() {
 282             match self.file.write(guard.remaining()) {
 283                 Ok(0) => {
 284                     self.res = Err(io::Error::new(
 285                         io::ErrorKind::WriteZero,
 286                         "failed to write the buffered data",
 287                     ));
 288                     return;
 289                 }
 290                 Ok(n) => guard.consume(n),
 291                 Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
 292                 Err(e) => {
 293                     self.res = Err(e);
 294                     return;
 295                 }
 296             }
 297         }
 298     }
 299
 300     #[inline]
 301     fn capacity(&self) -> usize {
 302         self.buf.len()
 303     }
 304
 305     #[inline]
 306     fn write_one(&mut self, value: u8) {
 307         // We ensure this during `FileEncoder` construction.
 308         debug_assert!(self.capacity() >= 1);
 309
 310         let mut buffered = self.buffered;
 311
 312         if std::intrinsics::unlikely(buffered >= self.capacity()) {
 313             self.flush();
 314             buffered = 0;
 315         }
 316
 317         // SAFETY: The above check and `flush` ensures that there is enough
 318         // room to write the input to the buffer.
 319         unsafe {
 320             *MaybeUninit::slice_as_mut_ptr(&mut self.buf).add(buffered) = value;
 321         }
 322
 323         self.buffered = buffered + 1;
 324     }
 325
 326     #[inline]
 327     fn write_all(&mut self, buf: &[u8]) {
 328         let capacity = self.capacity();
 329         let buf_len = buf.len();
 330
 331         if std::intrinsics::likely(buf_len <= capacity) {
 332             let mut buffered = self.buffered;
 333
 334             if std::intrinsics::unlikely(buf_len > capacity - buffered) {
 335                 self.flush();
 336                 buffered = 0;
 337             }
 338
 339             // SAFETY: The above check and `flush` ensures that there is enough
 340             // room to write the input to the buffer.
 341             unsafe {
 342                 let src = buf.as_ptr();
 343                 let dst = MaybeUninit::slice_as_mut_ptr(&mut self.buf).add(buffered);
 344                 ptr::copy_nonoverlapping(src, dst, buf_len);
 345             }
 346
 347             self.buffered = buffered + buf_len;
 348         } else {
 349             self.write_all_unbuffered(buf);
 350         }
 351     }
 352
 353     fn write_all_unbuffered(&mut self, mut buf: &[u8]) {
 354         // If we've already had an error, do nothing. It'll get reported after
 355         // `finish` is called.
 356         if self.res.is_err() {
 357             return;
 358         }
 359
 360         if self.buffered > 0 {
 361             self.flush();
 362         }
 363
 364         // This is basically a copy of `Write::write_all` but also updates our
 365         // `self.flushed`. It's necessary because `Write::write_all` does not
 366         // return the number of bytes written when an error is encountered, and
 367         // without that, we cannot accurately update `self.flushed` on error.
 368         while !buf.is_empty() {
 369             match self.file.write(buf) {
 370                 Ok(0) => {
 371                     self.res = Err(io::Error::new(
 372                         io::ErrorKind::WriteZero,
 373                         "failed to write whole buffer",
 374                     ));
 375                     return;
 376                 }
 377                 Ok(n) => {
 378                     buf = &buf[n..];
 379                     self.flushed += n;
 380                 }
 381                 Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
 382                 Err(e) => {
 383                     self.res = Err(e);
 384                     return;
 385                 }
 386             }
 387         }
 388     }
 389
 390     pub fn finish(mut self) -> Result<usize, io::Error> {
 391         self.flush();
 392
 393         let res = std::mem::replace(&mut self.res, Ok(()));
 394         res.map(|()| self.position())
 395     }
 396 }
 397
 398 impl Drop for FileEncoder {
 399     fn drop(&mut self) {
 400         // Likely to be a no-op, because `finish` should have been called and
 401         // it also flushes. But do it just in case.
 402         let _result = self.flush();
 403     }
 404 }
 405
 406 macro_rules! file_encoder_write_leb128 {
 407     ($enc:expr, $value:expr, $int_ty:ty, $fun:ident) => {{
 408         const MAX_ENCODED_LEN: usize = max_leb128_len!($int_ty);
 409
 410         // We ensure this during `FileEncoder` construction.
 411         debug_assert!($enc.capacity() >= MAX_ENCODED_LEN);
 412
 413         let mut buffered = $enc.buffered;
 414
 415         // This can't overflow. See assertion in `FileEncoder::with_capacity`.
 416         if std::intrinsics::unlikely(buffered + MAX_ENCODED_LEN > $enc.capacity()) {
 417             $enc.flush();
 418             buffered = 0;
 419         }
 420
 421         // SAFETY: The above check and flush ensures that there is enough
 422         // room to write the encoded value to the buffer.
 423         let buf = unsafe {
 424             &mut *($enc.buf.as_mut_ptr().add(buffered) as *mut [MaybeUninit<u8>; MAX_ENCODED_LEN])
 425         };
 426
 427         let encoded = leb128::$fun(buf, $value);
 428         $enc.buffered = buffered + encoded.len();
 429     }};
 430 }
 431
 432 impl Encoder for FileEncoder {
 433     #[inline]
 434     fn emit_usize(&mut self, v: usize) {
 435         file_encoder_write_leb128!(self, v, usize, write_usize_leb128)
 436     }
 437
 438     #[inline]
 439     fn emit_u128(&mut self, v: u128) {
 440         file_encoder_write_leb128!(self, v, u128, write_u128_leb128)
 441     }
 442
 443     #[inline]
 444     fn emit_u64(&mut self, v: u64) {
 445         file_encoder_write_leb128!(self, v, u64, write_u64_leb128)
 446     }
 447
 448     #[inline]
 449     fn emit_u32(&mut self, v: u32) {
 450         file_encoder_write_leb128!(self, v, u32, write_u32_leb128)
 451     }
 452
 453     #[inline]
 454     fn emit_u16(&mut self, v: u16) {
 455         self.write_all(&v.to_le_bytes());
 456     }
 457
 458     #[inline]
 459     fn emit_u8(&mut self, v: u8) {
 460         self.write_one(v);
 461     }
 462
 463     #[inline]
 464     fn emit_isize(&mut self, v: isize) {
 465         file_encoder_write_leb128!(self, v, isize, write_isize_leb128)
 466     }
 467
 468     #[inline]
 469     fn emit_i128(&mut self, v: i128) {
 470         file_encoder_write_leb128!(self, v, i128, write_i128_leb128)
 471     }
 472
 473     #[inline]
 474     fn emit_i64(&mut self, v: i64) {
 475         file_encoder_write_leb128!(self, v, i64, write_i64_leb128)
 476     }
 477
 478     #[inline]
 479     fn emit_i32(&mut self, v: i32) {
 480         file_encoder_write_leb128!(self, v, i32, write_i32_leb128)
 481     }
 482
 483     #[inline]
 484     fn emit_i16(&mut self, v: i16) {
 485         self.write_all(&v.to_le_bytes());
 486     }
 487
 488     #[inline]
 489     fn emit_i8(&mut self, v: i8) {
 490         self.emit_u8(v as u8);
 491     }
 492
 493     #[inline]
 494     fn emit_bool(&mut self, v: bool) {
 495         self.emit_u8(if v { 1 } else { 0 });
 496     }
 497
 498     #[inline]
 499     fn emit_f64(&mut self, v: f64) {
 500         let as_u64: u64 = v.to_bits();
 501         self.emit_u64(as_u64);
 502     }
 503
 504     #[inline]
 505     fn emit_f32(&mut self, v: f32) {
 506         let as_u32: u32 = v.to_bits();
 507         self.emit_u32(as_u32);
 508     }
 509
 510     #[inline]
 511     fn emit_char(&mut self, v: char) {
 512         self.emit_u32(v as u32);
 513     }
 514
 515     #[inline]
 516     fn emit_str(&mut self, v: &str) {
 517         self.emit_usize(v.len());
 518         self.emit_raw_bytes(v.as_bytes());
 519         self.emit_u8(STR_SENTINEL);
 520     }
 521
 522     #[inline]
 523     fn emit_raw_bytes(&mut self, s: &[u8]) {
 524         self.write_all(s);
 525     }
 526 }
 527
 528 // -----------------------------------------------------------------------------
 529 // Decoder
 530 // -----------------------------------------------------------------------------
 531
 532 pub struct MemDecoder<'a> {
 533     pub data: &'a [u8],
 534     position: usize,
 535 }
 536
 537 impl<'a> MemDecoder<'a> {
 538     #[inline]
 539     pub fn new(data: &'a [u8], position: usize) -> MemDecoder<'a> {
 540         MemDecoder { data, position }
 541     }
 542
 543     #[inline]
 544     pub fn position(&self) -> usize {
 545         self.position
 546     }
 547
 548     #[inline]
 549     pub fn set_position(&mut self, pos: usize) {
 550         self.position = pos
 551     }
 552
 553     #[inline]
 554     pub fn advance(&mut self, bytes: usize) {
 555         self.position += bytes;
 556     }
 557 }
 558
 559 macro_rules! read_leb128 {
 560     ($dec:expr, $fun:ident) => {{ leb128::$fun($dec.data, &mut $dec.position) }};
 561 }
 562
 563 impl<'a> Decoder for MemDecoder<'a> {
 564     #[inline]
 565     fn read_u128(&mut self) -> u128 {
 566         read_leb128!(self, read_u128_leb128)
 567     }
 568
 569     #[inline]
 570     fn read_u64(&mut self) -> u64 {
 571         read_leb128!(self, read_u64_leb128)
 572     }
 573
 574     #[inline]
 575     fn read_u32(&mut self) -> u32 {
 576         read_leb128!(self, read_u32_leb128)
 577     }
 578
 579     #[inline]
 580     fn read_u16(&mut self) -> u16 {
 581         let bytes = [self.data[self.position], self.data[self.position + 1]];
 582         let value = u16::from_le_bytes(bytes);
 583         self.position += 2;
 584         value
 585     }
 586
 587     #[inline]
 588     fn read_u8(&mut self) -> u8 {
 589         let value = self.data[self.position];
 590         self.position += 1;
 591         value
 592     }
 593
 594     #[inline]
 595     fn read_usize(&mut self) -> usize {
 596         read_leb128!(self, read_usize_leb128)
 597     }
 598
 599     #[inline]
 600     fn read_i128(&mut self) -> i128 {
 601         read_leb128!(self, read_i128_leb128)
 602     }
 603
 604     #[inline]
 605     fn read_i64(&mut self) -> i64 {
 606         read_leb128!(self, read_i64_leb128)
 607     }
 608
 609     #[inline]
 610     fn read_i32(&mut self) -> i32 {
 611         read_leb128!(self, read_i32_leb128)
 612     }
 613
 614     #[inline]
 615     fn read_i16(&mut self) -> i16 {
 616         let bytes = [self.data[self.position], self.data[self.position + 1]];
 617         let value = i16::from_le_bytes(bytes);
 618         self.position += 2;
 619         value
 620     }
 621
 622     #[inline]
 623     fn read_i8(&mut self) -> i8 {
 624         let value = self.data[self.position];
 625         self.position += 1;
 626         value as i8
 627     }
 628
 629     #[inline]
 630     fn read_isize(&mut self) -> isize {
 631         read_leb128!(self, read_isize_leb128)
 632     }
 633
 634     #[inline]
 635     fn read_bool(&mut self) -> bool {
 636         let value = self.read_u8();
 637         value != 0
 638     }
 639
 640     #[inline]
 641     fn read_f64(&mut self) -> f64 {
 642         let bits = self.read_u64();
 643         f64::from_bits(bits)
 644     }
 645
 646     #[inline]
 647     fn read_f32(&mut self) -> f32 {
 648         let bits = self.read_u32();
 649         f32::from_bits(bits)
 650     }
 651
 652     #[inline]
 653     fn read_char(&mut self) -> char {
 654         let bits = self.read_u32();
 655         std::char::from_u32(bits).unwrap()
 656     }
 657
 658     #[inline]
 659     fn read_str(&mut self) -> &'a str {
 660         let len = self.read_usize();
 661         let sentinel = self.data[self.position + len];
 662         assert!(sentinel == STR_SENTINEL);
 663         let s = unsafe {
 664             std::str::from_utf8_unchecked(&self.data[self.position..self.position + len])
 665         };
 666         self.position += len + 1;
 667         s
 668     }
 669
 670     #[inline]
 671     fn read_raw_bytes(&mut self, bytes: usize) -> &'a [u8] {
 672         let start = self.position;
 673         self.position += bytes;
 674         &self.data[start..self.position]
 675     }
 676 }
 677
 678 // Specializations for contiguous byte sequences follow. The default implementations for slices
 679 // encode and decode each element individually. This isn't necessary for `u8` slices when using
 680 // opaque encoders and decoders, because each `u8` is unchanged by encoding and decoding.
 681 // Therefore, we can use more efficient implementations that process the entire sequence at once.
 682
 683 // Specialize encoding byte slices. This specialization also applies to encoding `Vec<u8>`s, etc.,
 684 // since the default implementations call `encode` on their slices internally.
 685 impl Encodable<MemEncoder> for [u8] {
 686     fn encode(&self, e: &mut MemEncoder) {
 687         Encoder::emit_usize(e, self.len());
 688         e.emit_raw_bytes(self);
 689     }
 690 }
 691
 692 impl Encodable<FileEncoder> for [u8] {
 693     fn encode(&self, e: &mut FileEncoder) {
 694         Encoder::emit_usize(e, self.len());
 695         e.emit_raw_bytes(self);
 696     }
 697 }
 698
 699 // Specialize decoding `Vec<u8>`. This specialization also applies to decoding `Box<[u8]>`s, etc.,
 700 // since the default implementations call `decode` to produce a `Vec<u8>` internally.
 701 impl<'a> Decodable<MemDecoder<'a>> for Vec<u8> {
 702     fn decode(d: &mut MemDecoder<'a>) -> Self {
 703         let len = Decoder::read_usize(d);
 704         d.read_raw_bytes(len).to_owned()
 705     }
 706 }
 707
 708 // An integer that will always encode to 8 bytes.
 709 pub struct IntEncodedWithFixedSize(pub u64);
 710
 711 impl IntEncodedWithFixedSize {
 712     pub const ENCODED_SIZE: usize = 8;
 713 }
 714
 715 impl Encodable<MemEncoder> for IntEncodedWithFixedSize {
 716     #[inline]
 717     fn encode(&self, e: &mut MemEncoder) {
 718         let _start_pos = e.position();
 719         e.emit_raw_bytes(&self.0.to_le_bytes());
 720         let _end_pos = e.position();
 721         debug_assert_eq!((_end_pos - _start_pos), IntEncodedWithFixedSize::ENCODED_SIZE);
 722     }
 723 }
 724
 725 impl Encodable<FileEncoder> for IntEncodedWithFixedSize {
 726     #[inline]
 727     fn encode(&self, e: &mut FileEncoder) {
 728         let _start_pos = e.position();
 729         e.emit_raw_bytes(&self.0.to_le_bytes());
 730         let _end_pos = e.position();
 731         debug_assert_eq!((_end_pos - _start_pos), IntEncodedWithFixedSize::ENCODED_SIZE);
 732     }
 733 }
 734
 735 impl<'a> Decodable<MemDecoder<'a>> for IntEncodedWithFixedSize {
 736     #[inline]
 737     fn decode(decoder: &mut MemDecoder<'a>) -> IntEncodedWithFixedSize {
 738         let _start_pos = decoder.position();
 739         let bytes = decoder.read_raw_bytes(IntEncodedWithFixedSize::ENCODED_SIZE);
 740         let value = u64::from_le_bytes(bytes.try_into().unwrap());
 741         let _end_pos = decoder.position();
 742         debug_assert_eq!((_end_pos - _start_pos), IntEncodedWithFixedSize::ENCODED_SIZE);
 743
 744         IntEncodedWithFixedSize(value)
 745     }
 746 }