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## Proposed Changes
Enable multiple database backends for the slasher, either MDBX (default) or LMDB. The backend can be selected using `--slasher-backend={lmdb,mdbx}`.
## Additional Info
In order to abstract over the two library's different handling of database lifetimes I've used `Box::leak` to give the `Environment` type a `'static` lifetime. This was the only way I could think of using 100% safe code to construct a self-referential struct `SlasherDB`, where the `OpenDatabases` refers to the `Environment`. I think this is OK, as the `Environment` is expected to live for the life of the program, and both database engines leave the database in a consistent state after each write. The memory claimed for memory-mapping will be freed by the OS and appropriately flushed regardless of whether the `Environment` is actually dropped.
We are depending on two `sigp` forks of `libmdbx-rs` and `lmdb-rs`, to give us greater control over MDBX OS support and LMDB's version.
1.7 KiB
Cross-compiling
Lighthouse supports cross-compiling, allowing users to run a binary on one
platform (e.g., aarch64) that was compiled on another platform (e.g.,
x86_64).
Instructions
Cross-compiling requires Docker,
rustembedded/cross and for the
current user to be in the docker group.
The binaries will be created in the target/ directory of the Lighthouse
project.
Targets
The Makefile in the project contains four targets for cross-compiling:
build-x86_64: builds an optimized version for x86_64 processors (suitable for most users).build-x86_64-portable: builds a version for x86_64 processors which avoids using some modern CPU instructions that are incompatible with older CPUs.build-aarch64: builds an optimized version for 64-bit ARM processors (suitable for Raspberry Pi 4).build-aarch64-portable: builds a version for 64-bit ARM processors which avoids using some modern CPU instructions. In practice, very few ARM processors lack the instructions necessary to run the faster non-portable build.
For more information about optimized vs portable builds see Portability.
Example
cd lighthouse
make build-aarch64
The lighthouse binary will be compiled inside a Docker container and placed
in lighthouse/target/aarch64-unknown-linux-gnu/release.
Feature Flags
When using the makefile the set of features used for building can be controlled with
the environment variable CROSS_FEATURES. See Feature
Flags for available features.