Mercury now support shared memory autorouting.

A single margo instance can be initialized and it will handle both
shared memory communication and remote ones.

If the endpoint of the RPC is local mercury will automatically use
shared memory.

Since there is only one margo instance all the duplicated code for
rpc/ipc have been unified and simplified considerably.

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The way in which client contact the server has changed.

 - Server initializes its own margo instance and generate the endpoint
communication string using `HG_Addr_self`.
 - This endpoint description string is written on the pid file
 - When the client library loads it will fetch the server endpoint
description from the pid file and will use that to contact the server.

margo, argobots and mercury have been updated. The abt-snoozer dep
required by margo it is not needed anymore.

RocksDB has been also updated to the lastest release

loggers can be now configured at execution time, by using environment
variables for both server and client.

Server:
 - ADAFS_LOG_LEVEL
 - ADAFS_DAEMON_LOG_PATH

Client:
 - ADAFS_LOG_LEVEL
 - ADAFS_PRELOAD_LOG_PATH

Avoid the usage of a custom cmake "find-module" for mercury.
Instead use the official exported target

Support for the following calls has been added:
 - opendir
 - readdir
 - closedir

The readdir call use the new RPC get_dirents that ask to all the
nodes (broadcast) about all the existing first-level entries
of a specific directory.

exposes a new  DB function that allows to retrieve all the
first-level entries of a specific directory.

Now that we use only relative path on daemon side,
also the initial creation of the root directory should be
use a relative path.

Acknowledge the main thread that the IO operation had terminate before
to actually close the file.

This is a "dirty" fix that waits to be refactored.

WARNING: Error on close will not be reported to the client that issued the IO
operation.

Data operation has been grouped under a ChunkStorage class
that will manage all the data backend operations.

The instance of this object is stored into the ADAFS_DATA sigleton.

The metadataDB class was using integer to return errors.
New exceptions classes has been introduced in order to be used as error
propagation method.

In this commit the MetadataDB::get function has been modified in order
to make use of exceptions.

During daemon setup, multiple spdloggers are configured.

Using spdlog::get("<LOGNAME>") is possible to retrieve those and use
them in other part of the code.

Paths are now made relative to the mountdir at client side.

The new relativize_path fucntion in the PreloadContext is used to check
if a path is relative to the pseudo-mount directory and to make it
relative

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.

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.

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

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.