Decodes an integer to its bit-representation and extracts the bits at specified indices to specified field names as a boolean.
The bits are indexed from 0 and can accept up to 64 bits (the length of a Long). If the value in the input field is larger, the lowest 64 bits will be used.
Parameter | Type | Required | Default Value | Description |
---|---|---|---|---|
field | string | required | The name of the field that should be decoded. | |
onlyTrue | boolean | optional[a] | false | If set to true , fields will only be added if their value in the bitfield is true ; any flags that are false will not be added. |
output | array of arrays of strings | required | A list of pairs of indices in the bit-representation and the field name it should be written to. | |
[a] Optional parameters use their default value unless explicitly set. |
bitfield:extractFlags()
Examples
Click
next to an example below to get the full details.Decode and Extract Bit Flags
Extract true
bits using the bitfield:extractFlags()
function
Query
bitfield:extractFlags(field="MemoryDescriptionFlags", onlyTrue=true, output=[
[0,INVALID_ADDRESS],
[1,CURRENT_STACK],
[2,JIT_DOTNET],
[3,MZ],
[4,CODE],
[5,MODULE],
[6,MAPPED],
[7,REFLECIVE_PE],
[8,JIT_FLASH],
[9,PRIMARY_MODULE],
[10,PRIVATE_MEMORY],
[11,KNOWN_FUNCTION],
[12,FREE_MEMORY]])
Introduction
The bitfield:extractFlags()
function can be
used to decode an integer to its bit-representation and extract
the true
bits at specified indices with specified
names. The fields will be named with the names of the set bits.
The bits are indexed from 0 and will include up to 64 bits. If the
value in the input field is larger, the lowest 64 bits will be
used. In this example, the
bitfield:extractFlags()
function is used to
decode the field MemoryDescriptionFlags and
extract its true
bits.
Example incoming data might look like this:
MemoryDescriptionFlags,1234 |
// corresponds to 10011010010 |
Step-by-Step
Starting with the source repository events.
- logscale
bitfield:extractFlags(field="MemoryDescriptionFlags", onlyTrue=true, output=[ [0,INVALID_ADDRESS], [1,CURRENT_STACK], [2,JIT_DOTNET], [3,MZ], [4,CODE], [5,MODULE], [6,MAPPED], [7,REFLECIVE_PE], [8,JIT_FLASH], [9,PRIMARY_MODULE], [10,PRIVATE_MEMORY], [11,KNOWN_FUNCTION], [12,FREE_MEMORY]])
Decodes the field MemoryDescriptionFlags and extracts the
true
bits at specified indices with specified names. The fields will be named with the names of the set bits. Event Result set.
Summary and Results
The query is used to decode an integer to its bit-representation
and extract the true
bits at specified indices with
specified names.
Sample output from the incoming example data:
CODE | CURRENT_STACK | FREE_MEMORY | INVALID_ADDRESS | JIT_DOTNET | JIT_FLASH | KNOWN_FUNCTION | MAPPED | MODULE | MZ | PRIMARY_MODULE | PRIVATE_MEMORY | REFLECIVE_PE |
---|---|---|---|---|---|---|---|---|---|---|---|---|
true | true | false | false | false | false | false | true | false | false | false | true | true |
Generate Temporary Event With Bit Flags For Troubleshooting
Generate temporary events with the createEvents()
function as part of the query to generate sample data for testing or troubleshooting
Query
createEvents(["flags=4"])
| kvParse()
| bitfield:extractFlags(
field=flags,
output=[
[1, ErrorFlag],
[2, WarningFlag]
])
Introduction
The bitfield:extractFlags()
can be used to
code an integer to its bit-representation and extract the bits
at specified indices to specified field names as a boolean. One
or multiple flags can be extracted from a bit field. The
createEvents()
function generates temporary
events as part of the query and is ideal for generating sample
data for testing or troubleshooting. The events are generated
with no extracted fields but createEvents()
can, advantageously, be combined with one of the many parsers.
For example, given raw strings in the format of key/value pairs,
the pairs can be parsed to fields using the
kvParse()
function.
In this example, the bit field is called flags
and
has the value 4
corresponding to the bit string
00000100
. The goal is to extract
two flags based on their bit value.
Step-by-Step
Starting with the source repository events.
- logscale
createEvents(["flags=4"])
Creates a temporary event that includes a new field named flag to be used for testing purposes. Bit flags are one or more (up to 32) Boolean values stored in a single number variable.
- logscale
| kvParse()
Parses the raw text looking for the key/value pairs and creates the corresponding fields in the event. In this case a single field named flags with the value
8
. - logscale
| bitfield:extractFlags( field=flags, output=[ [1, ErrorFlag], [2, WarningFlag] ])
When specifying the values for the bit field, values start from bit 0 (
2^0
or decimal 1). The invidual bit values are defined using an array of arrays. Each array index should specify the bit number (not literal value) and the field to be created. Each field will then be set totrue
if the bit was enabled in the compared field.In the above example,
ErrorFlag
located at bit 1 (2^1, decimal 2), andWarningFlag
located at index2
(decimal 4). Event Result set.
Summary and Results
The query is used to extract and match values to bit flags. Creating events based on bit flags are useful when testing and troubleshooting on values, as it is faster to compare values stored as bitmasks compared to a series of booleans. Furthermore, events based on bit flags uses considerably less memory.
Sample output from the incoming example data:
ErrorFlag | WarningFlag |
---|---|
false | true |