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The following commit(s) were added to refs/heads/branch-3.4.0 by this push:
new fdbc67b9a8f5 HADOOP-18987. Various fixes to FileSystem API docs (#6292)
fdbc67b9a8f5 is described below
commit fdbc67b9a8f52237acdeed7b46f442e6e597588a
Author: DieterDP <90392398+dieterdp...@users.noreply.github.com>
AuthorDate: Fri Feb 2 12:49:31 2024 +0100
HADOOP-18987. Various fixes to FileSystem API docs (#6292)
Contributed by Dieter De Paepe
---
.../src/site/markdown/filesystem/abortable.md | 3 +-
.../src/site/markdown/filesystem/filesystem.md | 97 +++++++++++-----------
.../site/markdown/filesystem/fsdatainputstream.md | 8 +-
.../src/site/markdown/filesystem/model.md | 28 ++++---
.../src/site/markdown/filesystem/notation.md | 8 +-
5 files changed, 75 insertions(+), 69 deletions(-)
diff --git
a/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/abortable.md
b/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/abortable.md
index 7e6ea01a8fe9..dc7677bd9a54 100644
---
a/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/abortable.md
+++
b/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/abortable.md
@@ -88,14 +88,13 @@ for example. output streams returned by the S3A FileSystem.
The stream MUST implement `Abortable` and `StreamCapabilities`.
```python
- if unsupported:
+if unsupported:
throw UnsupportedException
if not isOpen(stream):
no-op
StreamCapabilities.hasCapability("fs.capability.outputstream.abortable") ==
True
-
```
diff --git
a/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/filesystem.md
b/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/filesystem.md
index 5fba8a2515bb..518026876ba0 100644
---
a/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/filesystem.md
+++
b/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/filesystem.md
@@ -64,13 +64,13 @@ a protected directory, result in such an exception being
raised.
### `boolean isDirectory(Path p)`
- def isDirectory(FS, p)= p in directories(FS)
+ def isDir(FS, p) = p in directories(FS)
### `boolean isFile(Path p)`
- def isFile(FS, p) = p in files(FS)
+ def isFile(FS, p) = p in filenames(FS)
### `FileStatus getFileStatus(Path p)`
@@ -250,7 +250,7 @@ process.
changes are made to the filesystem, the result of `listStatus(parent(P))`
SHOULD
include the value of `getFileStatus(P)`.
-* After an entry at path `P` is created, and before any other
+* After an entry at path `P` is deleted, and before any other
changes are made to the filesystem, the result of `listStatus(parent(P))`
SHOULD
NOT include the value of `getFileStatus(P)`.
@@ -305,7 +305,7 @@ that they must all be listed, and, at the time of listing,
exist.
All paths must exist. There is no requirement for uniqueness.
forall p in paths :
- exists(fs, p) else raise FileNotFoundException
+ exists(FS, p) else raise FileNotFoundException
#### Postconditions
@@ -381,7 +381,7 @@ being completely performed.
Path `path` must exist:
- exists(FS, path) : raise FileNotFoundException
+ if not exists(FS, path) : raise FileNotFoundException
#### Postconditions
@@ -432,7 +432,7 @@ of data which must be collected in a single RPC call.
#### Preconditions
- exists(FS, path) else raise FileNotFoundException
+ if not exists(FS, path) : raise FileNotFoundException
### Postconditions
@@ -463,7 +463,7 @@ and 1 for file count.
#### Preconditions
- exists(FS, path) else raise FileNotFoundException
+ if not exists(FS, path) : raise FileNotFoundException
#### Postconditions
@@ -567,7 +567,7 @@ when writing objects to a path in the filesystem.
#### Postconditions
- result = integer >= 0
+ result = integer >= 0
The outcome of this operation is usually identical to `getDefaultBlockSize()`,
with no checks for the existence of the given path.
@@ -591,12 +591,12 @@ on the filesystem.
#### Preconditions
- if not exists(FS, p) : raise FileNotFoundException
+ if not exists(FS, p) : raise FileNotFoundException
#### Postconditions
- if len(FS, P) > 0: getFileStatus(P).getBlockSize() > 0
+ if len(FS, P) > 0 : getFileStatus(P).getBlockSize() > 0
result == getFileStatus(P).getBlockSize()
1. The outcome of this operation MUST be identical to the value of
@@ -654,12 +654,12 @@ No ancestor may be a file
forall d = ancestors(FS, p) :
if exists(FS, d) and not isDir(FS, d) :
- raise [ParentNotDirectoryException, FileAlreadyExistsException,
IOException]
+ raise {ParentNotDirectoryException, FileAlreadyExistsException,
IOException}
#### Postconditions
- FS' where FS'.Directories' = FS.Directories + [p] + ancestors(FS, p)
+ FS' where FS'.Directories = FS.Directories + [p] + ancestors(FS, p)
result = True
@@ -688,7 +688,7 @@ The return value is always true—even if a new
directory is not created
The file must not exist for a no-overwrite create:
- if not overwrite and isFile(FS, p) : raise FileAlreadyExistsException
+ if not overwrite and isFile(FS, p) : raise FileAlreadyExistsException
Writing to or overwriting a directory must fail.
@@ -698,7 +698,7 @@ No ancestor may be a file
forall d = ancestors(FS, p) :
if exists(FS, d) and not isDir(FS, d) :
- raise [ParentNotDirectoryException, FileAlreadyExistsException,
IOException]
+ raise {ParentNotDirectoryException, FileAlreadyExistsException,
IOException}
FileSystems may reject the request for other
reasons, such as the FS being read-only (HDFS),
@@ -712,8 +712,8 @@ For instance, HDFS may raise an `InvalidPathException`.
#### Postconditions
FS' where :
- FS'.Files'[p] == []
- ancestors(p) is-subset-of FS'.Directories'
+ FS'.Files[p] == []
+ ancestors(p) subset-of FS'.Directories
result = FSDataOutputStream
@@ -734,7 +734,7 @@ The behavior of the returned stream is covered in
[Output](outputstream.html).
clients creating files with `overwrite==true` to fail if the file is created
by another client between the two tests.
-* The S3A and potentially other Object Stores connectors not currently change
the `FS` state
+* The S3A and potentially other Object Stores connectors currently don't
change the `FS` state
until the output stream `close()` operation is completed.
This is a significant difference between the behavior of object stores
and that of filesystems, as it allows >1 client to create a file with
`overwrite=false`,
@@ -762,15 +762,15 @@ The behavior of the returned stream is covered in
[Output](outputstream.html).
#### Implementation Notes
`createFile(p)` returns a `FSDataOutputStreamBuilder` only and does not make
-change on filesystem immediately. When `build()` is invoked on the
`FSDataOutputStreamBuilder`,
+changes on the filesystem immediately. When `build()` is invoked on the
`FSDataOutputStreamBuilder`,
the builder parameters are verified and [`create(Path p)`](#FileSystem.create)
is invoked on the underlying filesystem. `build()` has the same preconditions
and postconditions as [`create(Path p)`](#FileSystem.create).
* Similar to [`create(Path p)`](#FileSystem.create), files are overwritten
-by default, unless specify `builder.overwrite(false)`.
+by default, unless specified by `builder.overwrite(false)`.
* Unlike [`create(Path p)`](#FileSystem.create), missing parent directories are
-not created by default, unless specify `builder.recursive()`.
+not created by default, unless specified by `builder.recursive()`.
### <a name='FileSystem.append'></a> `FSDataOutputStream append(Path p, int
bufferSize, Progressable progress)`
@@ -780,14 +780,14 @@ Implementations without a compliant call SHOULD throw
`UnsupportedOperationExcep
if not exists(FS, p) : raise FileNotFoundException
- if not isFile(FS, p) : raise [FileAlreadyExistsException,
FileNotFoundException, IOException]
+ if not isFile(FS, p) : raise {FileAlreadyExistsException,
FileNotFoundException, IOException}
#### Postconditions
FS' = FS
result = FSDataOutputStream
-Return: `FSDataOutputStream`, which can update the entry `FS.Files[p]`
+Return: `FSDataOutputStream`, which can update the entry `FS'.Files[p]`
by appending data to the existing list.
The behavior of the returned stream is covered in [Output](outputstream.html).
@@ -813,7 +813,7 @@ Implementations without a compliant call SHOULD throw
`UnsupportedOperationExcep
#### Preconditions
- if not isFile(FS, p)) : raise [FileNotFoundException, IOException]
+ if not isFile(FS, p)) : raise {FileNotFoundException, IOException}
This is a critical precondition. Implementations of some FileSystems (e.g.
Object stores) could shortcut one round trip by postponing their HTTP GET
@@ -842,7 +842,7 @@ The result MUST be the same for local and remote callers of
the operation.
symbolic links
1. HDFS throws `IOException("Cannot open filename " + src)` if the path
-exists in the metadata, but no copies of any its blocks can be located;
+exists in the metadata, but no copies of its blocks can be located;
-`FileNotFoundException` would seem more accurate and useful.
### `FSDataInputStreamBuilder openFile(Path path)`
@@ -861,7 +861,7 @@ Implementations without a compliant call MUST throw
`UnsupportedOperationExcepti
let stat = getFileStatus(Path p)
let FS' where:
- (FS.Directories', FS.Files', FS.Symlinks')
+ (FS'.Directories, FS.Files', FS'.Symlinks)
p' in paths(FS') where:
exists(FS, stat.path) implies exists(FS', p')
@@ -931,16 +931,16 @@ metadata in the `PathHandle` to detect references from
other namespaces.
### `FSDataInputStream open(PathHandle handle, int bufferSize)`
-Implementaions without a compliant call MUST throw
`UnsupportedOperationException`
+Implementations without a compliant call MUST throw
`UnsupportedOperationException`
#### Preconditions
let fd = getPathHandle(FileStatus stat)
if stat.isdir : raise IOException
let FS' where:
- (FS.Directories', FS.Files', FS.Symlinks')
- p' in FS.Files' where:
- FS.Files'[p'] = fd
+ (FS'.Directories, FS.Files', FS'.Symlinks)
+ p' in FS'.Files where:
+ FS'.Files[p'] = fd
if not exists(FS', p') : raise InvalidPathHandleException
The implementation MUST resolve the referent of the `PathHandle` following
@@ -951,7 +951,7 @@ encoded in the `PathHandle`.
#### Postconditions
- result = FSDataInputStream(0, FS.Files'[p'])
+ result = FSDataInputStream(0, FS'.Files[p'])
The stream returned is subject to the constraints of a stream returned by
`open(Path)`. Constraints checked on open MAY hold to hold for the stream, but
@@ -1006,7 +1006,7 @@ A directory with children and `recursive == False` cannot
be deleted
If the file does not exist the filesystem state does not change
- if not exists(FS, p):
+ if not exists(FS, p) :
FS' = FS
result = False
@@ -1089,7 +1089,7 @@ Some of the object store based filesystem implementations
always return
false when deleting the root, leaving the state of the store unchanged.
if isRoot(p) :
- FS ' = FS
+ FS' = FS
result = False
This is irrespective of the recursive flag status or the state of the
directory.
@@ -1152,7 +1152,7 @@ has been calculated.
Source `src` must exist:
- exists(FS, src) else raise FileNotFoundException
+ if not exists(FS, src) : raise FileNotFoundException
`dest` cannot be a descendant of `src`:
@@ -1162,7 +1162,7 @@ This implicitly covers the special case of `isRoot(FS,
src)`.
`dest` must be root, or have a parent that exists:
- isRoot(FS, dest) or exists(FS, parent(dest)) else raise IOException
+ if not (isRoot(FS, dest) or exists(FS, parent(dest))) : raise IOException
The parent path of a destination must not be a file:
@@ -1240,7 +1240,8 @@ There is no consistent behavior here.
The outcome is no change to FileSystem state, with a return value of false.
- FS' = FS; result = False
+ FS' = FS
+ result = False
*Local Filesystem*
@@ -1319,28 +1320,31 @@ Implementations without a compliant call SHOULD throw
`UnsupportedOperationExcep
All sources MUST be in the same directory:
- for s in sources: if parent(S) != parent(p) raise IllegalArgumentException
+ for s in sources:
+ if parent(s) != parent(p) : raise IllegalArgumentException
All block sizes must match that of the target:
- for s in sources: getBlockSize(FS, S) == getBlockSize(FS, p)
+ for s in sources:
+ getBlockSize(FS, s) == getBlockSize(FS, p)
No duplicate paths:
- not (exists p1, p2 in (sources + [p]) where p1 == p2)
+ let input = sources + [p]
+ not (exists i, j: i != j and input[i] == input[j])
HDFS: All source files except the final one MUST be a complete block:
for s in (sources[0:length(sources)-1] + [p]):
- (length(FS, s) mod getBlockSize(FS, p)) == 0
+ (length(FS, s) mod getBlockSize(FS, p)) == 0
#### Postconditions
FS' where:
- (data(FS', T) = data(FS, T) + data(FS, sources[0]) + ... + data(FS,
srcs[length(srcs)-1]))
- and for s in srcs: not exists(FS', S)
+ (data(FS', p) = data(FS, p) + data(FS, sources[0]) + ... + data(FS,
sources[length(sources)-1]))
+ for s in sources: not exists(FS', s)
HDFS's restrictions may be an implementation detail of how it implements
@@ -1360,7 +1364,7 @@ Implementations without a compliant call SHOULD throw
`UnsupportedOperationExcep
if not exists(FS, p) : raise FileNotFoundException
- if isDir(FS, p) : raise [FileNotFoundException, IOException]
+ if isDir(FS, p) : raise {FileNotFoundException, IOException}
if newLength < 0 || newLength > len(FS.Files[p]) : raise
HadoopIllegalArgumentException
@@ -1369,8 +1373,7 @@ Truncate cannot be performed on a file, which is open for
writing or appending.
#### Postconditions
- FS' where:
- len(FS.Files[p]) = newLength
+ len(FS'.Files[p]) = newLength
Return: `true`, if truncation is finished and the file can be immediately
opened for appending, or `false` otherwise.
@@ -1399,7 +1402,7 @@ Source and destination must be different
if src = dest : raise FileExistsException
```
-Destination and source must not be descendants one another
+Destination and source must not be descendants of one another
```python
if isDescendant(src, dest) or isDescendant(dest, src) : raise IOException
```
@@ -1429,7 +1432,7 @@ Given a base path on the source `base` and a child path
`child` where `base` is
```python
def final_name(base, child, dest):
- is base = child:
+ if base == child:
return dest
else:
return dest + childElements(base, child)
@@ -1557,7 +1560,7 @@ while (iterator.hasNext()) {
As raising exceptions is an expensive operation in JVMs, the `while(hasNext())`
loop option is more efficient. (see also [Concurrency and the Remote
Iterator](#RemoteIteratorConcurrency)
-for a dicussion on this topic).
+for a discussion on this topic).
Implementors of the interface MUST support both forms of iterations; authors
of tests SHOULD verify that both iteration mechanisms work.
diff --git
a/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/fsdatainputstream.md
b/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/fsdatainputstream.md
index f64a2bd03b63..3820d0b8af67 100644
---
a/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/fsdatainputstream.md
+++
b/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/fsdatainputstream.md
@@ -55,7 +55,7 @@ with access functions:
file as returned by `FileSystem.getFileStatus(Path p)`
forall p in dom(FS.Files[p]) :
- len(data(FSDIS)) == FS.getFileStatus(p).length
+ len(data(FSDIS)) == FS.getFileStatus(p).length
### `Closeable.close()`
@@ -259,8 +259,8 @@ Examples: `RawLocalFileSystem` , `HttpFSFileSystem`
If the operation is supported and there is a new location for the data:
- FSDIS' = (pos, data', true)
- result = True
+ FSDIS' = (pos, data', true)
+ result = True
The new data is the original data (or an updated version of it, as covered
in the Consistency section below), but the block containing the data at
`offset`
@@ -268,7 +268,7 @@ is sourced from a different replica.
If there is no other copy, `FSDIS` is not updated; the response indicates
this:
- result = False
+ result = False
Outside of test methods, the primary use of this method is in the
{{FSInputChecker}}
class, which can react to a checksum error in a read by attempting to source
diff --git
a/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/model.md
b/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/model.md
index e121c92deedd..7507d7a10392 100644
--- a/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/model.md
+++ b/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/model.md
@@ -108,21 +108,21 @@ such as `rename`.
## Defining the Filesystem
-A filesystem `FS` contains a set of directories, a dictionary of paths and a
dictionary of symbolic links
+A filesystem `FS` contains directories (a set of paths), files (a mapping of a
path to a list of bytes) and symlinks (a set of paths mapping to paths)
- (Directories:Set[Path], Files:[Path:List[byte]], Symlinks:Set[Path])
+ (Directories:Set[Path], Files:Map[Path:List[byte]],
Symlinks:Map[Path:Path])
Accessor functions return the specific element of a filesystem
- def FS.Directories = FS.Directories
+ def directories(FS) = FS.Directories
def files(FS) = FS.Files
- def symlinks(FS) = FS.Symlinks
+ def symlinks(FS) = keys(FS.Symlinks)
def filenames(FS) = keys(FS.Files)
The entire set of a paths finite subset of all possible Paths, and functions
to resolve a path to data, a directory predicate or a symbolic link:
- def paths(FS) = FS.Directories + filenames(FS) + FS.Symlinks)
+ def paths(FS) = FS.Directories + filenames(FS) + symlinks(FS)
A path is deemed to exist if it is in this aggregate set:
@@ -169,10 +169,10 @@ in a set, hence no children with duplicate names.
A path *D* is a descendant of a path *P* if it is the direct child of the
path *P* or an ancestor is a direct child of path *P*:
- def isDescendant(P, D) = parent(D) == P where isDescendant(P, parent(D))
+ def isDescendant(P, D) = parent(D) == P or isDescendant(P, parent(D))
The descendants of a directory P are all paths in the filesystem whose
-path begins with the path P -that is their parent is P or an ancestor is P
+path begins with the path P, i.e. their parent is P or an ancestor is P
def descendants(FS, D) = {p for p in paths(FS) where isDescendant(D, p)}
@@ -181,7 +181,7 @@ path begins with the path P -that is their parent is P or
an ancestor is P
A path MAY refer to a file that has data in the filesystem; its path is a key
in the data dictionary
- def isFile(FS, p) = p in FS.Files
+ def isFile(FS, p) = p in keys(FS.Files)
### Symbolic references
@@ -193,6 +193,10 @@ A path MAY refer to a symbolic link:
### File Length
+Files store data:
+
+ def data(FS, p) = files(FS)[p]
+
The length of a path p in a filesystem FS is the length of the data stored, or
0 if it is a directory:
def length(FS, p) = if isFile(p) : return length(data(FS, p)) else return 0
@@ -215,9 +219,9 @@ This may differ from the local user account name.
A path cannot refer to more than one of a file, a directory or a symbolic link
- FS.Directories ^ keys(data(FS)) == {}
- FS.Directories ^ symlinks(FS) == {}
- keys(data(FS))(FS) ^ symlinks(FS) == {}
+ directories(FS) ^ filenames(FS) == {}
+ directories(FS) ^ symlinks(FS) == {}
+ filenames(FS) ^ symlinks(FS) == {}
This implies that only files may have data.
@@ -248,7 +252,7 @@ For all files in an encrypted zone, the data is encrypted,
but the encryption
type and specification are not defined.
forall f in files(FS) where inEncyptionZone(FS, f):
- isEncrypted(data(f))
+ isEncrypted(data(FS, f))
## Notes
diff --git
a/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/notation.md
b/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/notation.md
index 472bb5dd7ddb..e82e17a993da 100644
---
a/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/notation.md
+++
b/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/notation.md
@@ -80,15 +80,15 @@ are used as the basis for this syntax as it is both plain
ASCII and well-known.
##### Lists
-* A list *L* is an ordered sequence of elements `[e1, e2, ... en]`
+* A list *L* is an ordered sequence of elements `[e1, e2, ... e(n)]`
* The size of a list `len(L)` is the number of elements in a list.
* Items can be addressed by a 0-based index `e1 == L[0]`
-* Python slicing operators can address subsets of a list `L[0:3] == [e1,e2]`,
`L[:-1] == en`
+* Python slicing operators can address subsets of a list `L[0:3] ==
[e1,e2,e3]`, `L[:-1] == [e1, ... e(n-1)]`
* Lists can be concatenated `L' = L + [ e3 ]`
* Lists can have entries removed `L' = L - [ e2, e1 ]`. This is different from
Python's
`del` operation, which operates on the list in place.
* The membership predicate `in` returns true iff an element is a member of a
List: `e2 in L`
-* List comprehensions can create new lists: `L' = [ x for x in l where x < 5]`
+* List comprehensions can create new lists: `L' = [ x for x in L where x < 5]`
* for a list `L`, `len(L)` returns the number of elements.
@@ -130,7 +130,7 @@ Strings are lists of characters represented in double
quotes. e.g. `"abc"`
All system state declarations are immutable.
-The suffix "'" (single quote) is used as the convention to indicate the state
of the system after an operation:
+The suffix "'" (single quote) is used as the convention to indicate the state
of the system after a mutating operation:
L' = L + ['d','e']
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