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Overview
Comment: | Describe an enhancement to manifest artifacts that allows for an hierarchical description of the structure of a check-in. It is hoped that this new format will work more efficiently for large repositories, and make clone and pull from Git much easier and faster. This check-in is a documentation change only. the new hierarchical manifest type has not yet been implemented in code. |
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Downloads: | Tarball | ZIP archive | SQL archive |
Timelines: | family | ancestors | descendants | both | hierarchical-manifests |
Files: | files | file ages | folders |
SHA1: |
7576a0f1b979662ea6ecec4ab3cd009a |
User & Date: | drh 2015-12-22 07:18:28 |
Context
2015-12-22
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13:40 | Further design changes to hierarchical manifests. Still no actual code. ... (check-in: 47aa9282 user: drh tags: hierarchical-manifests) | |
07:18 | Describe an enhancement to manifest artifacts that allows for an hierarchical description of the structure of a check-in. It is hoped that this new format will work more efficiently for large repositories, and make clone and pull from Git much easier and faster. This check-in is a documentation change only. the new hierarchical manifest type has not yet been implemented in code. ... (check-in: 7576a0f1 user: drh tags: hierarchical-manifests) | |
2015-12-20
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02:02 | Make use of the new $ROOT feature in the on-line documentation. ... (check-in: 60486250 user: drh tags: trunk) | |
Changes
Changes to www/fileformat.wiki.
1 2 3 4 5 6 7 8 9 10 11 12 13 | <title>Fossil File Formats</title> <h1 align="center"> Fossil File Formats </h1> The global state of a fossil repository is kept simple so that it can endure in useful form for decades or centuries. A fossil repository is intended to be readable, searchable, and extensible by people not yet born. The global state of a fossil repository is an unordered set of <i>artifacts</i>. An artifact might be a source code file, the text of a wiki page, | | | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | <title>Fossil File Formats</title> <h1 align="center"> Fossil File Formats </h1> The global state of a fossil repository is kept simple so that it can endure in useful form for decades or centuries. A fossil repository is intended to be readable, searchable, and extensible by people not yet born. The global state of a fossil repository is an unordered set of <i>artifacts</i>. An artifact might be a source code file, the text of a wiki page, part of a trouble ticket, or one of several special artifacts used to show the relationships between other artifacts within the project. Each artifact is normally represented on disk as a separate file. Artifacts can be text or binary. In addition to the global state, each fossil repository also contains local state. The local state consists of web-page formatting |
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31 32 33 34 35 36 37 | Each artifact in the repository is named by its SHA1 hash. No prefixes or meta information is added to an artifact before its hash is computed. The name of an artifact in the repository is exactly the same SHA1 hash that is computed by sha1sum on the file as it exists in your source tree.</p> | < < < < < < < < < < < < < < < | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | < < < < < < < < < < < < < < < < < < < < | 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 | Each artifact in the repository is named by its SHA1 hash. No prefixes or meta information is added to an artifact before its hash is computed. The name of an artifact in the repository is exactly the same SHA1 hash that is computed by sha1sum on the file as it exists in your source tree.</p> In the current implementation (as of 2015-12-23) the artifacts that make up a fossil repository are stored as delta- and zlib-compressed blobs in an <a href="http://www.sqlite.org/">SQLite</a> database. This is an implementation detail and might change in a future release. For the purpose of this article "file format" means the format of the artifacts, not how the artifacts are stored on disk. It is the artifact format that is intended to be enduring. The specifics of how artifacts are stored on disk, though stable, is not intended to live as long as the artifact format. All of the artifacts can be extracted from a Fossil repository using the "fossil deconstruct" command. <h2>1.0 Special Artifacts</h2> Some artifacts have a particular format which gives them special meaning to fossil. Fossil recognizes: <ul> <li> [#manifest | Manifests] </li> <li> [#directory | Directories] </li> <li> [#cluster | Clusters] </li> <li> [#ctrl | Tags] </li> <li> [#wikichng | Wiki Pages] </li> <li> [#tktchng | Ticket Changes] </li> <li> [#attachment | Attachments] </li> <li> [#event | TechNotes] </li> </ul> Any artifact is not one of the above eight special artifacts is a "content" artifact. Every distinct version of every file under management is a content artifact, as are attachments to wiki pages and tickets. Any artifact that follows the appropriate syntactic rules is a special artifact. It is possible for the same artifact to be used as both a special artifact and a content artifact, thought this is rare and probably undesirable. (Future versions of Fossil might restrict attempts to check-in special artifacts as content files.) To prevent accidental occurrences of the same artifact being used as both a special artifact and a content artifact, the syntactic rules for special artifacts are very strict. All special artifacts are pure UTF8 text. Newline characters (ASCII 0x0a) separate the artifact into "cards". Each card begins with a single character "card type". Zero or more arguments may follow the card type. All arguments are separated from each other and from the card-type character by a single space character (ASCII 0x20). There is no surplus white space between arguments and no leading or trailing whitespace except for the newline character that acts as the card separator. All cards of a special artifact occur in strict sorted lexicographical order. No card may be duplicated. Some special artifacts (example: [#manifest|manifests]) may be PGP clear-signed, but otherwise special artifacts may contain no additional text or data. <a name="manifest"></a> <h2>1.1 The Manifest Artifact</h2> A manifest defines a check-in or version of the project source tree. The manifest contains a list of artifacts for each file in the project and the corresponding filenames, as well as information such as parent check-ins, the name of the programmer who created the check-in, the date and time when the check-in was created, and any check-in comments associated with the check-in. Allowed cards in the manifest are as follows: <blockquote> <b>B</b> <i>baseline-manifest</i><br> <b>C</b> <i>checkin-comment</i><br> <b>D</b> <i>time-and-date-stamp</i><br> <b>F</b> <i>filename</i> ?<i>SHA1-hash</i>? ?<i>permissions</i>? ?<i>old-name</i>?<br> |
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124 125 126 127 128 129 130 131 132 133 134 | escape sequences are applied to the text: A space (ASCII 0x20) is represented as "\s" (ASCII 0x5C, 0x73). A newline (ASCII 0x0a) is "\n" (ASCII 0x5C, x6E). A backslash (ASCII 0x5C) is represented as two backslashes "\\". Apart from space and newline, no other whitespace characters are allowed in the check-in comment. Nor are any unprintable characters allowed in the comment. A manifest must have exactly one D-card. The sole argument to the D-card is a date-time stamp in the ISO8601 format. The date and time should be in coordinated universal time (UTC). | > > > > | | > | > > | | > | > | > > | > | > > > > > > > | > > > > > > > | 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 | escape sequences are applied to the text: A space (ASCII 0x20) is represented as "\s" (ASCII 0x5C, 0x73). A newline (ASCII 0x0a) is "\n" (ASCII 0x5C, x6E). A backslash (ASCII 0x5C) is represented as two backslashes "\\". Apart from space and newline, no other whitespace characters are allowed in the check-in comment. Nor are any unprintable characters allowed in the comment. A manifest has zero or one N-cards. The N-card specifies the mimetype for the text in the comment of the C-card. If the N-card is omitted, a default mimetype is used. A manifest must have exactly one D-card. The sole argument to the D-card is a date-time stamp in the ISO8601 format. The date and time should be in coordinated universal time (UTC). The format must be one of: <blockquote> <i>YYYY</i><b>-</b><i>MM</i><b>-</b><i>DD</i><b>T</b><i>HH</i><b>:</b><i>MM</i><b>:</b><i>SS</i><br> <i>YYYY</i><b>-</b><i>MM</i><b>-</b><i>DD</i><b>T</b><i>HH</i><b>:</b><i>MM</i><b>:</b><i>SS</i><b>.</b><i>SSS</i> </blockquote> A manifest has zero or more F-cards. Each F-card identifies a file or subdirectory that is part of the check-in. There are one, two, three, or four arguments. The first argument is the pathname of the file or subdirectory in the check-in relative to the root of the project file hierarchy. No ".." or "." directories are allowed within the filename. Space characters are escaped as in C-card comment text. Backslash characters and newlines are not allowed within filenames. The directory separator character is a forward slash (ASCII 0x2F). The second argument to the F-card is the full 40-character lower-case hexadecimal SHA1 hash of the content artifact, or of the [#directory|directory artifact] if the "d" permission is present. The second argument is required for baseline manifests but is optional for delta manifests. When the second argument to the F-card is omitted, it means that the file has been deleted relative to the baseline (files removed in baseline manifests versions are <em>not</em> added as F-cards). The optional 3rd argument defines any special access permissions associated with the file. This can be defined as "x" to mean that the file is executable or "l" (small letter ell) to mean a symlink or "d" to mean the entry describes a subdirectory rather than a file. All files and subdirectories are always readable and writable. This can be expressed by "w" permission if desired but the "w" permission is optional and is ignored by Fossil. The file format might be extended with new permission letters in the future. The optional 4th argument is the name of the same file as it existed in the parent check-in. If the name of the file is unchanged from its parent, then the 4th argument is omitted. Manifests may be either flat or hierarchical. A flat manifest lists all files in the check-in, including all files in subdirectories. A flat manifest may not include F-cards with the "d" permission. An heirarchical manifest only lists the files or subdirectories at the top-level of the check-in. An heirarchical manifest may not include an F-card entries that have a directory separator character ("/"). An heirarchical manifest may not be a delta-manifest (it may not have a B-card) nor may it be used as a baseline-manifest by some other delta-manifest. Hierarchical manifests are only recognized by Fossil versions 1.35 and later. Repositories that contain hierarchical manifests will cause problems for earlier versions of Fossil. When an F-card refers to a subdirectory (that is to say, when the F-card is part of an hierarchical manifest and contains the "d" permission) then the referenced directory artifact must be a [#directory|well-formed directory artifact] that contains a G-card that exactly matches the name of the subdirectory as assigned by the F-card. If these conditions are not met, then the artifact is not a valid manifest. A manifest has zero or one P-cards. Most manifests have one P-card. The P-card has a varying number of arguments that defines other manifests from which the current manifest is derived. Each argument is an 40-character lowercase hexadecimal SHA1 of the predecessor manifest. All arguments to the P-card must be unique to that line. |
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232 233 234 235 236 237 238 239 240 | of all prior lines of the manifest up to and including the newline character that immediately precedes the "Z". The Z-card is a sanity check to prove that the manifest is well-formed and consistent. A sample manifest from Fossil itself can be seen [/artifact/28987096ac | here]. <a name="cluster"></a> | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | | < < < < < < < < < < < < < < < | | | | | < < < | | | | | 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 | of all prior lines of the manifest up to and including the newline character that immediately precedes the "Z". The Z-card is a sanity check to prove that the manifest is well-formed and consistent. A sample manifest from Fossil itself can be seen [/artifact/28987096ac | here]. <a name="directory"></a> <h3>1.2 Directory Artifacts</h3> A directory artifact describes the files and subdirectories within a single directory of an hierarchical manifest. Directory artifacts are only recognized by Fossil version 1.35 and later (circa 2015-12-23). Directory artifacts contain zero or more F-cards and exactly one Z-card, in the same format as a manifest. A directory artifact also contains exactly one G-card with a single argument that is the pathname of the directory relative to the root of the repository. The format of the directory name in a G-card is the same as the format of a filename in an F-card. The F-cards in a directory artifact may not contain directory separator characters. The content of subdirectories must be expressed using additional directory artifacts referenced by F-cards with the "d" permission. All F-cards in a directory artifact must contain at least two arguments. When an F-card X of directory artifact Y refers to subdirectory Z (that is to say, when F-card X contains the "d" permission and the second argument on X is the SHA1 hash of directory artifact Z) then the G-card of Z must be the concatenation of the G-card on artifact Y, the directory separator character "/" and the first argument to the F-card X. Otherwise, the artifact Y is not a valid directory artifact. <a name="cluster"></a> <h3>1.3 Clusters Artifacts</h3> A cluster is an artifact that declares the existence of other artifacts. Clusters are used during repository synchronization to help reduce network traffic. As such, clusters are an optimization and may be removed from a repository without loss or damage to the underlying project code. Clusters may not be PGP clearsigned. Allowed cards in the cluster are as follows: <blockquote> <b>M</b> <i>artifact-id</i><br /> <b>Z</b> <i>checksum</i> </blockquote> A cluster contains one or more "M" cards followed by a single "Z" line. Each M card has a single argument which is the artifact ID of another artifact in the repository. The Z card work exactly like the Z card of a manifest. The argument to the Z card is the lower-case hexadecimal representation of the MD5 checksum of all prior cards in the cluster. The Z-card is required. An example cluster from Fossil can be seen [/artifact/d03dbdd73a2a8 | here]. <a name="ctrl"></a> <h3>1.4 Tag Artifacts</h3> Tag artifacts are used to assign properties to other artifacts within the repository. Tag artifacts where called "control artifacts" in an earlier version of this document. Though their name has changed in the documentation, their function has not. Allowed cards in a tag artifact are as follows: <blockquote> <b>D</b> <i>time-and-date-stamp</i><br /> <b>T</b> (<b>+</b>|<b>-</b>|<b>*</b>)<i>tag-name</i> <i>artifact-id</i> ?<i>value</i>?<br /> <b>U</b> <i>user-name</i><br /> <b>Z</b> <i>checksum</i><br /> </blockquote> A tag artifact must have one D card, one U card, one Z card and one or more T cards. No other cards or other text is allowed in a control artifact. Tag artifacts might be PGP clearsigned. The D card and the Z card of a tag artifact are the same as in a manifest. The T card represents a [./branching.wiki#tags | tag or property] that is applied to some other artifact. The T card has two or three values. The second argument is the 40 character lowercase artifact ID of the artifact to which the tag is to be applied. The |
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331 332 333 334 335 336 337 | check-in user. The "date" tag overrides the check-in date. The "branch" tag sets the name of the branch that at check-in belongs to. Symbolic tags begin with the "sym-" prefix. The U card is the name of the user that created the control artifact. The Z card is the usual required artifact checksum. | | | | < < | | 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 | check-in user. The "date" tag overrides the check-in date. The "branch" tag sets the name of the branch that at check-in belongs to. Symbolic tags begin with the "sym-" prefix. The U card is the name of the user that created the control artifact. The Z card is the usual required artifact checksum. An example tag artifacts can be seen [/info/9d302ccda8 | here]. <a name="wikichng"></a> <h3>1.5 Wiki Pages</h3> A wiki artifact defines a single version of a single wiki page. Wiki artifacts accept the following card types: <blockquote> <b>D</b> <i>time-and-date-stamp</i><br /> <b>L</b> <i>wiki-title</i><br /> <b>N</b> <i>mimetype</i><br /> <b>P</b> <i>parent-artifact-id</i>+<br /> |
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372 373 374 375 376 377 378 | that terminates the W card. The wiki text is always followed by one extra newline. An example wiki artifact can be seen [/artifact?name=7b2f5fd0e0&txt=1 | here]. <a name="tktchng"></a> | | | 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 | that terminates the W card. The wiki text is always followed by one extra newline. An example wiki artifact can be seen [/artifact?name=7b2f5fd0e0&txt=1 | here]. <a name="tktchng"></a> <h3>1.6 Ticket Changes</h3> A ticket-change artifact represents a change to a trouble ticket. The following cards are allowed on a ticket change artifact: <blockquote> <b>D</b> <i>time-and-date-stamp</i><br /> <b>J</b> ?<b>+</b>?<i>name</i> ?<i>value</i>?<br /> |
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418 419 420 421 422 423 424 | The field name and value are both encoded using the character escapes defined for the C card of a manifest. An example ticket-change artifact can be seen [/artifact/91f1ec6af053 | here]. <a name="attachment"></a> | | | 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 | The field name and value are both encoded using the character escapes defined for the C card of a manifest. An example ticket-change artifact can be seen [/artifact/91f1ec6af053 | here]. <a name="attachment"></a> <h3>1.7 Attachments</h3> An attachment artifact associates some other artifact that is the attachment (the source artifact) with a ticket or wiki page or technical note to which the attachment is connected (the target artifact). The following cards are allowed on an attachment artifact: |
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460 461 462 463 464 465 466 | If an attachment is added anonymously, then the U card may be omitted. The Z card is the usual checksum over the rest of the attachment artifact. The Z card is required. <a name="event"></a> | | | 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 | If an attachment is added anonymously, then the U card may be omitted. The Z card is the usual checksum over the rest of the attachment artifact. The Z card is required. <a name="event"></a> <h3>1.8 Technical Notes</h3> A technical note or "technote" artifact (formerly known as an "event" artifact) associates a timeline comment and a page of text (similar to a wiki page) with a point in time. Technotes can be used to record project milestones, release notes, blog entries, process checkpoints, or news articles. The following cards are allowed on an technote artifact: |
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507 508 509 510 511 512 513 | from which the current technote is an edit. The P card is a hint to the system that it might be space efficient to store one technote as a delta of the other. A technote might contain one or more T-cards used to set [./branching.wiki#tags | tags or properties] on the technote. The format of the T-card is the same as | | | 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 | from which the current technote is an edit. The P card is a hint to the system that it might be space efficient to store one technote as a delta of the other. A technote might contain one or more T-cards used to set [./branching.wiki#tags | tags or properties] on the technote. The format of the T-card is the same as described in [#ctrl | Tag Artifacts] section above, except that the second argument is the single character "<b>*</b>" instead of an artifact ID and the name is always prefaced by "<b>+</b>". The <b>*</b> in place of the artifact ID indicates that the tag or property applies to the current artifact. It is not possible to encode the current artifact ID as part of an artifact, since the act of inserting the artifact ID would change the artifact ID, hence a <b>*</b> is used to represent "self". The "<b>+</b>" on the |
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529 530 531 532 533 534 535 | technote. The format of the W card is exactly the same as for a [#wikichng | wiki artifact]. The Z card is the required checksum over the rest of the artifact. <a name="summary"></a> | | | > | > > | > > > > > > > > > > > > > > > > > > > > > > > > > > > > | | | | | 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 | technote. The format of the W card is exactly the same as for a [#wikichng | wiki artifact]. The Z card is the required checksum over the rest of the artifact. <a name="summary"></a> <h2>2.0 Card Summary</h2> The following table summarizes the various kinds of cards that appear on Fossil artifacts. A blank entry means that combination of card and artifact is not legal. A number or range of numbers indicates the number of times a card may (or must) appear in the corresponding artifact type. e.g. a value of 1 indicates a required unique card and 1+ indicates that one or more such cards are required. <table border=1 width="100%"> <tr> <th rowspan=2 valign=bottom>Card Format</th> <th colspan=8>Used By</th> </tr> <tr> <th>Manifest</th> <th>Directory</th> <th>Cluster</th> <th>Tag</th> <th>Wiki</th> <th>Ticket</th> <th>Attachment</th> <th>Technote</th> </tr> <tr> <td><b>A</b> <i>filename</i> <i>target</i> ?<i>source</i>?</td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td align=center><b>1</b></td> <td> </td> </tr> <tr> <td><b>B</b> <i>baseline</i></td> <td align=center><b>0-1*</b></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr><td> </td><td colspan='8'>* = Required for delta manifests, Disallowed for hierarchical manifests.</td></tr> <tr> <td><b>C</b> <i>comment-text</i></td> <td align=center><b>1</b></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td align=center><b>0-1</b></td> <td align=center><b>0-1</b></td> </tr> <tr> <td><b>D</b> <i>date-time-stamp</i></td> <td align=center><b>1</b></td> <td> </td> <td> </td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> </tr> <tr> <td><b>E</b> <i>technote-time technote-id</i></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td align=center><b>1</b></td> </tr> <tr> <td><b>F</b> <i>filename</i> ?<i>uuid</i>? ?<i>permissions</i>? ?<i>oldname</i>?</td> <td align=center><b>0+</b></td> <td align=center><b>0+</b></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><b>G</b> <i>fileame</i> <td> </td> <td align=center><b>1</b></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><b>J</b> <i>name</i> ?<i>value</i>?</td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td align=center><b>1+</b></td> <td> </td> <td> </td> </tr> <tr> <td><b>K</b> <i>ticket-uuid</i></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td align=center><b>1</b></td> <td> </td> <td> </td> </tr> <tr> <td><b>L</b> <i>wiki-title</i></td> <td> </td> <td> </td> <td> </td> <td> </td> <td align=center><b>1</b></td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><b>M</b> <i>uuid</i></td> <td> </td> <td> </td> <td align=center><b>1+</b></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><b>N</b> <i>mimetype</i></td> <td align=center><b>0-1</b></td> <td> </td> <td> </td> <td> </td> <td align=center><b>0-1</b></td> <td> </td> <td align=center><b>0-1</b></td> <td align=center><b>0-1</b></td> </tr> <tr> <td><b>P</b> <i>uuid ...</i></td> <td align=center><b>0-1</b></td> <td> </td> <td> </td> <td> </td> <td align=center><b>0-1</b></td> <td> </td> <td> </td> <td align=center><b>0-1</b></td> </tr> <tr> <td><b>Q</b> (<b>+</b>|<b>-</b>)<i>uuid</i> ?<i>uuid</i>?</td> <td align=center><b>0+</b></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <td><b>R</b> <i>md5sum</i></td> <td align=center><b>0-1</b></td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <td> </td> <tr> <td><b>T</b> (<b>+</b>|<b>*</b>|<b>-</b>)<i>tagname</i> <i>uuid</i> ?<i>value</i>?</td> <td align=center><b>0+</b></td> <td> </td> <td> </td> <td align=center><b>1+</b></td> <td> </td> <td> </td> <td> </td> <td align=center><b>0+</b></td> </tr> <tr> <td><b>U</b> <i>username</i></td> <td align=center><b>1</b></td> <td> </td> <td> </td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>0-1</b></td> <td align=center><b>0-1</b></td> </tr> <tr> <td><b>W</b> <i>size</i></td> <td> </td> <td> </td> <td> </td> <td> </td> <td align=center><b>1</b></td> <td> </td> <td> </td> <td align=center><b>1</b></td> </tr> <tr> <td><b>Z</b> <i>md5sum</i></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> <td align=center><b>1</b></td> </tr> </table> <a name="addenda"></a> <h2>3.0 Addenda</h2> This section contains additional information about the low-level artifact formats of Fossil. <h3>3.1 R-Card Hash Calculation</h3> Given a manifest file named <tt>MF</tt>, the following Bash shell code demonstrates how to compute the value of the R card in that manifest. This example uses manifest [28987096ac]. Lines starting with <tt>#</tt> are shell input and other lines are output. This demonstration assumes that the file versions represented by the input manifest are checked out under the current directory. |
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779 780 781 782 783 784 785 | filenames in the manifest are "fossilized" (encoded) because they contain spaces. In that case the shell-generated hash would differ because the <tt>stat</tt> calls will fail to find such files (which are output in encoded form here). That approach also won't work for delta manifests. Calculating the R-card for delta manifests requires traversing both the delta and its baseline in lexical order of the files, preferring the delta's copy if both contain a given file. | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > | 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 | filenames in the manifest are "fossilized" (encoded) because they contain spaces. In that case the shell-generated hash would differ because the <tt>stat</tt> calls will fail to find such files (which are output in encoded form here). That approach also won't work for delta manifests. Calculating the R-card for delta manifests requires traversing both the delta and its baseline in lexical order of the files, preferring the delta's copy if both contain a given file. <h3>3.2 Different Kinds Of Manifest Artifacts</h3> The original (1.0) version of Fossil only supported flat baseline manifests. That means that all the files of a check-in had to be listed in every manifest. Because manifests are delta-encoded, there is not a storage space issue. Fossil was originally designed specifically to support the SQLite project, and as SQLite has fewer than 2000 files on any give version, a flat baseline manifest design worked well there and was simple to implement. However, some project (ex: NetBSD) contain a huge number of files in every version, and even though the manifests compressed will using delta-compression, many CPU cycles had to be spent to decompress those manifests. To help make Fossil more efficient for large projects like NetBSD, the concept of a delta-manifest was added. This helped a lot but was not a perfect solution. Later, the concept of an hierarchical manifest was added. By breaking up each manifest into many separate subdirectories it is hoped that the processing of projects with many files can be better optimized. The hierarchical manifest design also more closely resembles the low-level file format used by Git, thus making pull and clone from Git repositories easier. In retrospect, it would have been better if Fossil had only hierarchical manifests. But as there are many legacy repositories that use flat manifests and delta manifests, all three forms must be supported moving forward. |