com.android.tools.lint.checks

Class ApiDatabase

java.lang.Object

com.android.tools.lint.checks.ApiDatabase

Direct Known Subclasses:

ApiLookup

public class ApiDatabase
extends java.lang.Object

Database for API checking, providing efficient lookup for a given class, method or field.

This class provides a binary cache around an API to make initialization faster and to require fewer objects. It creates a binary cache data structure which fits in a single byte array, meaning that to open the database you can just read in the byte array and go. On one particular machine, this takes about 30-50 ms versus seconds for the full parse. It also helps memory by placing everything in a compact byte array instead of needing separate strings (2 bytes per character in a char[] for the 25k method entries, 11k field entries and 6k class entries) - and it also avoids the same number of Map.Entry objects.

Note: It stores the strings as single bytes, since all the JVM signatures are in ASCII.

Field Summary

Fields

Modifier and Type	Field and Description
static int	API_MASK
protected int	containerCount
protected static boolean	DEBUG_SEARCH
protected static java.lang.String	FILE_HEADER
static int	HAS_EXTRA_BYTE_FLAG
protected byte[]	mData
protected int[]	mIndices
protected static boolean	WRITE_STATS

Constructor Summary

Constructors

Constructor and Description
ApiDatabase()

Method Summary

Modifier and Type	Method and Description
protected static int	compare(byte[] data, int offset, byte terminator, java.lang.String s, int sOffset, int max)
protected java.lang.String	dumpEntry(int offset)
protected int	findClass(java.lang.String className) Returns the class number of the given class, or -1 if it is unknown.
protected int	findContainer(java.lang.String packageOrClassName, int containerNameLength, boolean packageOnly) Returns the container index of the given package or class, or -1 if it is unknown.
protected static int	get2ByteInt(byte[] data, int offset)
protected static int	get3ByteInt(byte[] mData, int offset)
protected static int	get4ByteInt(byte[] data, int offset)
static int	getBinaryFormatVersion(int majorBinaryFormatVersion) Computes the binary format version
protected static void	put2ByteInt(java.nio.ByteBuffer buffer, int value)
protected static void	put3ByteInt(java.nio.ByteBuffer buffer, int value)
protected void	readData(com.android.tools.lint.client.api.LintClient client, java.io.File binaryFile, com.android.tools.lint.checks.ApiDatabase.CacheCreator cacheCreator, int majorBinaryFormatVersion) Database format:
protected static void	writeDatabase(java.io.File file, com.android.tools.lint.checks.Api<? extends ApiClassBase> info, int majorBinaryFormatVersion) See the readData(LintClient, File, CacheCreator, int) for documentation on the data format.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

FILE_HEADER

protected static final java.lang.String FILE_HEADER

See Also:

Constant Field Values

DEBUG_SEARCH

protected static final boolean DEBUG_SEARCH

See Also:

Constant Field Values

WRITE_STATS

protected static final boolean WRITE_STATS

See Also:

Constant Field Values

HAS_EXTRA_BYTE_FLAG

public static final int HAS_EXTRA_BYTE_FLAG

See Also:

Constant Field Values

API_MASK

public static final int API_MASK

See Also:

Constant Field Values

mData

protected byte[] mData

mIndices

protected int[] mIndices

containerCount

protected int containerCount

Constructor Detail

ApiDatabase

public ApiDatabase()

Method Detail

getBinaryFormatVersion

public static int getBinaryFormatVersion(int majorBinaryFormatVersion)

Computes the binary format version

This is a byte, the first 3 bits of which are from the specified by subclasses (which can change the representation of the custom API attributes), and the remaining 5 bits are a minor version from this class (BINARY_FORMAT_VERSION), which controls the binary representation of most of the Api.

Parameters:

majorBinaryFormatVersion - which must fit in 3 bits (therefore less than 8)

Returns:

the computed binary format version

readData

protected void readData(@NonNull
                        com.android.tools.lint.client.api.LintClient client,
                        @NonNull
                        java.io.File binaryFile,
                        @NonNull
                        com.android.tools.lint.checks.ApiDatabase.CacheCreator cacheCreator,
                        int majorBinaryFormatVersion)

Database format:

 (Note: all numbers are big endian; the format uses 1, 2, 3 and 4 byte integers.)


 1. A file header, which is the exact contents of FILE_HEADER encoded
     as ASCII characters. The purpose of the header is to identify what the file
     is for, for anyone attempting to open the file.
 2. A file version number. If the binary file does not match the reader's expected
     version, it can ignore it (and regenerate the cache from XML).

 3. The index table. When the data file is read, this is used to initialize the
    mIndices array. The index table is built up like this:
    a. The number of index entries (e.g. number of elements in the mIndices array)
        [a 4-byte integer]
    b. The number of java/javax packages [a 4-byte integer]
    c. Offsets to the container entries, one for each package or a class containing inner
       classes [a 4-byte integer].
    d. Offsets to the class entries, one for each class [a 4-byte integer].
    e. Offsets to the member entries, one for each member [a 4-byte integer].

 4. The member entries -- one for each member. A given class entry will point to the
    first and last members in the index table above, and the offset of a given member
    is pointing to the offset of these entries.
    a. The name and description (except for the return value) of the member, in JVM format
       (e.g. for toLowerCase(char) we'd have "toLowerCase(C)". This is converted into
       UTF_8 representation as bytes [n bytes, the length of the byte representation of
       the description).
    b. A terminating 0 byte [1 byte].
    c. A sequence of bytes representing custom data attached to this entry, to be interpreted
       by the consumer.
       All bytes except the last one have the top bit (HAS_EXTRA_BYTE_FLAG) set.

 5. The class entries -- one for each class.
    a. The index within this class entry where the metadata (other than the name)
       can be found. [1 byte]. This means that if you know a class by its number,
       you can quickly jump to its metadata without scanning through the string to
       find the end of it, by just adding this byte to the current offset and
       then you're at the data described below for (d).
    b. The name of the class (just the base name, not the package), as encoded as a
       UTF-8 string. [n bytes]
    c. A terminating 0 [1 byte].
    d. The index in the index table (3) of the first member in the class [a 3-byte integer.]
    e. The number of members in the class [a 2-byte integer].
    f. Custom metadata associated with the class.

 6. The container entries -- one for each package and for each class containing inner classes.
    a. The name of the package or the outer class [n bytes].
    b. A terminating 0 for packages, or 1 for outer classes [1 byte].
    c. The index in the index table (3) of the first class in the package or the first inner
       class [a 3-byte integer.]
    d. The number of classes in the package or the number of inner classes in the outer class
       [a 2-byte integer].
 

writeDatabase

protected static void writeDatabase(java.io.File file,
                                    com.android.tools.lint.checks.Api<? extends ApiClassBase> info,
                                    int majorBinaryFormatVersion)
                             throws java.io.IOException

See the readData(LintClient, File, CacheCreator, int) for documentation on the data format.

Throws:

java.io.IOException

get4ByteInt

protected static int get4ByteInt(@NonNull
                                 byte[] data,
                                 int offset)

put3ByteInt

protected static void put3ByteInt(@NonNull
                                  java.nio.ByteBuffer buffer,
                                  int value)

put2ByteInt

protected static void put2ByteInt(@NonNull
                                  java.nio.ByteBuffer buffer,
                                  int value)

get3ByteInt

protected static int get3ByteInt(@NonNull
                                 byte[] mData,
                                 int offset)

get2ByteInt

protected static int get2ByteInt(@NonNull
                                 byte[] data,
                                 int offset)

dumpEntry

protected java.lang.String dumpEntry(int offset)

compare

protected static int compare(byte[] data,
                             int offset,
                             byte terminator,
                             java.lang.String s,
                             int sOffset,
                             int max)

findContainer

protected int findContainer(@NonNull
                            java.lang.String packageOrClassName,
                            int containerNameLength,
                            boolean packageOnly)

Returns the container index of the given package or class, or -1 if it is unknown.

findClass

protected int findClass(@NonNull
                        java.lang.String className)

Returns the class number of the given class, or -1 if it is unknown.