The new PreloadContext class is used as singleton to store the general context
information of the interception library.

The plan is to move global accessed variables into this sigleton.

At the moment just the logger object has been moved into it.

Fix update size

See merge request zdvresearch_bsc/adafs!57

Metadata::serialize() was appending result instead of ovewriting it.

The new approach is to make serialize function return a new constructed
string instead of accepting a string reference to fill.

bump RocksDB version to `5.12.4`

See merge request zdvresearch_bsc/adafs!56

Daemon cleanup includes

See merge request zdvresearch_bsc/adafs!54

Signed-off-by: Marc Vef <vef@uni-mainz.de>

Refactor stat

See merge request zdvresearch_bsc/adafs!55

Signed-off-by: Marc Vef <vef@uni-mainz.de>

The rpc stat handler was the only one calling directly a db function,
bypassing the intermediate adafs_ops interface.

A new function on the adafs_ops interface has been added to be used by
the rpc stat handler.

Cmake fixes

See merge request zdvresearch_bsc/adafs!53

Signed-off-by: Marc Vef <vef@uni-mainz.de>

gflags is needed to compile rocksDB but not to link with it

Setting the properly the JMALLOC_LIBRARIES variable into the find module
made possible to avoid the conditonal inclusion of the library

Atomic operations

See merge request zdvresearch_bsc/adafs!52

Signed-off-by: Marc Vef <vef@uni-mainz.de>

Tommaso Tocci authored Apr 19, 2018 and Marc Vef committed Apr 27, 2018

The creation was performed through a simple rocksDB PUT operation.

Multiple creation attempts on the same file would override the
previously inserted metadata, in particular the file size.

The creation is now handled with a new MergeOperand.
Now a creation attampt on an already existing file will be converted in
a NOP.

Tommaso Tocci authored Apr 19, 2018 and Marc Vef committed Apr 27, 2018

The new MergeOperand base class can be subclassed in order to implement
new merge-operands with their specific parameters and semantics.

Tommaso Tocci authored Apr 19, 2018 and Marc Vef committed Apr 27, 2018

The UpdateSizeOperand has been renamed IncreaseSizeOperand.

The operand was using three parameters size,offset and append_flag.

Since we only need the (size + offset) sum in order to apply the
operand, the offset field has been removed.

Tommaso Tocci authored Apr 17, 2018 and Marc Vef committed Apr 27, 2018

In order to make the file-size-update operation atomic it is necessary
to make the following action atomic:

 - READ old size value from rocksDB
 - COMPUTE new size based on the write operation
 - WRITE back the new value rocksDB

We use rocksDB merge operation [1] in order to implement the atomic update.

[1]: https://github.com/facebook/rocksdb/wiki/Merge-Operator

Tommaso Tocci authored Apr 17, 2018 and Marc Vef committed Apr 27, 2018

with the current storage back-end, chunks of a file are stored in
several files in a folder on a real kernel-space filesystem.

Removing a file means that we need to remove the entire directory and
all its sub-files (rm -r).
This operation is not atomic and it can raise errors if performed
concurrently..

This commit handles properly this kind of errors.

Intercept remove call

See merge request zdvresearch_bsc/adafs!48

Use special file name "nonexisting" for testing non existing file

Various fix for dependencies compile script

See merge request zdvresearch_bsc/adafs!47