Decode and Extract true Bits as Strings - Example 1 | LogScale Query Examples

Decode and Extract `true` Bits as Strings - Example 1

Decode and extract true bits as strings using the bitfield:extractFlagsAsString() function

Query

logscale

bitfield:extractFlagsAsString(field="MemoryDescriptionFlags", flagNames=[
[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:extractFlagsAsString() function can be used to decode an integer to its bit-representation and extract the true bits at specified indices with specified names to a string. The flags are listed in ascending order, from lowest bit to highest bit. 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:extractFlagsAsString() function is used to decode the field MemoryDescriptionFlags and extract its true bits.

Example incoming data might look like this:

Raw Events

MemoryDescriptionFlags,1234

// corresponds to 10011010010

Step-by-Step

Starting with the source repository events.
flowchart LR; %%{init: {"flowchart": {"defaultRenderer": "elk"}} }%% repo{{Events}} 0[/Filter/] result{{Result Set}} repo --> 0 0 --> result style 0 fill:#ff0000,stroke-width:4px,stroke:#000;
logscale
```
bitfield:extractFlagsAsString(field="MemoryDescriptionFlags", flagNames=[
[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 to a string in a field named _flags. The string will contain the names of the set bits, listed in ascending order, from lowest bit to highest bit.
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 to a string.

Sample output from the incoming example data:

_flags
CURRENT_STACK CODE MAPPED REFLECIVE_PE PRIVATE_MEMORY

Examples Library